Lemme brake it down for ya.
Without investing incredible amounts of money and time (machining adapters for calipers and floating disks, GSXR frontend swaps, etc.), here are your options to improve your front brakes:
New/rebuilt MC
Stainless brake lines
New brake pads
Fully rebuilt caliper (seal, piston if pitted, cleaned bore and passages).
If you still aren't satisfied once you've done that (at this point you're gonna be $100-150 in the hole with just one brake), you can try a dual disk setup. Search for "dual disk CB550" and you should find plenty. I wish I could tell you that there is an easy, modern, and cheap alternative to these early disc brake systems, but there isn't.
Seth