Front caliber CB 350 vs 750

would a cb750 front brake caliber be good for the cb350?

It wouldn't fit without a custom bracket, correctly spaced and mounted and an adapted disc. Better bet would be to find another CB/CL series that has bigger brakes than the 350 and that has the same diameter forks and swap the front end. Rebuild the caliper no matter what, and have the disc skimmed true. New brake fluid, banjo bolts, maybe new lines. Safety first. Good luck.

What's the difference between the two? Because in the pics the only thing different I see is where the brake line connects to the caliper.

They look the same until you see them on a bench side by side.
CB250 twin, 350T & F, 360, 400f, 500f & Twin & 550f all use same caliper.
What is wrong with the one you have (or don't you have one?)
I have several 360 calipers, plus spares.
Most need cleaning and painting though