Man that's a good looking bike, I'd ride the hell out of it just as is with some cleaning and soft part replacements anyway. If you're gonna repaint, get some replacement parts and paint those, that blue/white on the tank is awesome, even if its a little dinged or scratched up it has more character than then just a white paint job. If it was me I would clean it up and wax or clear it and call it done.
I think you might find there is just about the same amount of aftermarket stuff for those stock carbs as there are for the mikunis, nothing against them I've had lots of luck getting mine to run fine, however closer you keep things to stock the better they work, slapping pods on the back of them will cause all kinds of issues.
Next time you need to pull the shifter just take the bolt out and drive a flat head screwdriver into the slot at the back to expand it. Should slide right off then. Be careful chain kits as some of the larger sized ones will rub the clutch actuating arm inside the cover and rip it apart. Cleaning in there is nothing more than getting a can of degreaser and spraying it around. No real need to clean up since it will end up dirty anyway, can check seals for leaks while you are in there any way, make sure the washer is still locked in place on the shift shaft with a cir-clip. If the clip looks remotely loose replace it, that's one of the main problems with 450's, will cause funky or hard shifting. Make sure you don't loose the ball bearing in the clutch actuator.
If you haven't gotten one already copy of of the HONDA shop manual can be had
here
I suggest getting comfy with that engine, they are wonderful little pieces of art that have internals that look like sewing machines. Get something wrong they run like crap or don't at all. Get em right they have more than enough power to hang with just about everything out there today. Still surprises me how much power mine makes sometimes.