Clip-Ons and front end stiffness?

I've got a little over 100 miles on the "Sweep the Floor 2" CB550 bike and it's running great. The suspension is pretty stiff, though. This bike was built from leftovers and parts from various bikes.

I read up on CB1100F shocks and made adjustments there (though they may always be a little stiff, as the springs have been cut. That's why my buddy gave them to me. They are the correct length for a CB550 now, though).

The front forks are CB750. I don't have a clue what year they're from and I know different years used different fork oil amounts. It's been so long since I did them that I can't remember how much oil I used.
Because 750 forks are longer that 550 forks, I was able to push them up through the triple and install the clip on's above the top triple. The length from the bottom triple to the axle is still stock 550 length.

The front end seems very stiff. I'm considering letting out a little oil from each fork until I get the feel I want.
Do Clip On bars transmit more "shock" to the rider? Even pushing down on the front end in the driveway, it seems very stiff. I'm wondering if I used too much oil for whatever year forks I have?

Have you checked your preload/sag it should be about 30-35 mm for the street.
Depending on how you like it.
I'm used to working on forks with a spacer that can cut off.
It would be interesting to see how the inside of your forks are laid out

They're just stock CB750 forks, though I'm unsure if I have the correct amount/weight of oil in them since I don't know what year they're from and it changed over the years.

They are SOHC4 CB750 shocks.

The bike doesn't have a center stand. I should be able to pull one fork cap at a time and check for a spacer and measure the length without the front end collapsing, right?

I used CB750 fork tubes and springs in my 550 but used the original fork lowers.
Also used Girling CB750 rear shocks and still ran out of ground clearance a few times.
It isn't in service manual but the best way to set fork oil is by the height of oil in tubes.
Remove springs, compress forks, use a syringe to remove or add oil
You don't need a special gauge, just a piece of tube with a length of coat hanger to keep it straight
The amount is irrelevant, just start at 6" from the top and add or remove 1/2" at a time until your happy with how they react.
It's easiest to do the first fill with forks upright in a bench vice but doing them fitted to bike works as long as you realise measurement will be slightly out
Always cycle forks a few times before replacing springs and top caps
There shouldn't be any spacers inside and btw, pulling a top cap with bike on sidestand is a real bad idea.
Your better off with a scissor jack under right side frame tube to lift front end off the ground (you can get hold of scissor jacks from junk yard pretty cheap if you don't already have one)

Stiff as in rock hard or can you push through it?

Stiff as in I can push through it but way too stiff.
It handles fine on smooth roads, but big dips or a road with frost heaves and it gets too jumpy.

I could only push down through about a third of their travel, when it should be closer to 3/4.
It's been pointed out to me that the 750 is sprung for an additional 90 lbs. I did use my graduated cylinder and a syringe to remove 12cc from the drain hole of each fork. That seems to have helped in the "grab the brake and push down" test. I'll ride it again later on and see if it actually did anything, though it did give me more travel....about 1/2 way now.

90 lbs is a LOT of difference. You may need to get softer springs before you are happy. Sounds like you can try less oil since your first reduction made such an obvious difference. The air volume above the oil is a big component of the spring pressure especially as the volume of air gets smaller due to more oil. The less air there is to compress the more rapid the pressure increase as the forks compress so too much oil becomes very noticeable. Check the sag. That's the amount the forks compress with just the weight of bike and rider on them like when you are riding with no bumps. About 1/3 of the total travel is a good place to start. If less you likely will need softer springs.

I would say something is wrong somewhere as the CB750 wallows like a pig in shit because suspension was way too soft. It was just about right for 550 though

I set the shocks to the softest settings all the way around (3 adjustments on 1100F shocks) and took 12cc of oil out of each shock. That definitely helped, but the front end is still a little stiff. I may try removing a little more oil.

Eventually, I'll probably call Race Tech or Progressive and ge some replacement springs for both ends. Or, if I stumble across a set of 550 springs for the forks, grab those and make some spacers....just as an experiment if nothing else.

I can get a set of Progressive fork springs, model #11-1104, for a really good price. These are the springs that come with a spacer. Here are some specs from the Progressive site:

Free length: 19.12"/486mm
Spring rate: 35/50 lbs./in or .63/.89 kg/mm
Spacer: 1.30 inches

If these are the ones that are softer WITHOUT the spacer, I'm thinking about giving them a try and then contacting Progressive about springs for the rear shocks.
Any input on springs for the shocks? The 1100F shocks are ~13.25" from eye to eye and the spring itself is only about 8" long on the softest setting.
What's a good length and spring rate to keep that approximate ride height on a ~415 lb. bike with a 180 lb. rider?