Can I switch out '77 750K seat with '76 CB750F seat

[Cafesomeday]

Subject pretty much says it all. I'm looking at a 1976 CB750 Supersport seat that I'd like to pick up, but not sure if it will fit on my 77 K. I know that 77's frame is longer than the previous years and I think its the same length as the supersports, but not sure if the seat pan will match up with the current hinges. Anyone know?

On a second note (maybe should have started another thread for this), my engine is running pretty hot - my pipes melted through the rubber on my clutch cable which were zip-tied to the frame - and I think its because the previous owner put a 4-1 exhaust without re-jetting. So, the main jets are 120 (I'm pretty sure), how much larger should I go? Just up to 122? Would this potentially solve my problem? If I figure out a way to keep my cables safe, is there any great danger to the engine running it like this for a couple of months?

Thanks for your help guys.

[Re-run]

Well lets look at seats first. the 76 seat will fit BUT the hinges and locks are on opposite sides. So those would need to be flipped around and all the jazz. Also there may or may not be a gap between the tank and the seat, or it could rub. Take a measurement of your seat and see if you can get one of the 76.

As for the exhaust being hot, it is a 77, it is made to run lean. Moving up in main jets will get you nothing really. The mains really only effect the upper 75% throttle range much. Instead, check your plugs and see what color the insulator is. On my 78, I shoot for a LIGHT tan, anything more is too rich.
I know some people who have put in pod filters and did not have to rejet with these carbs so a 4-1 will certainly not need a rejet. If anything, you can either raise your needle in each carb by lowering the clip 1 space or turn the idle mix.

The idle mix screws are true fuel screws and give you a great amount of leverage in tuning. Remember though, out is RICHER and in is LEANER.

If the plugs are not completely white, you should be just fine. just move the cable away from the pipes.

[Cafesomeday]

Wow, thanks Re-run, quick response time. I'll check all that out. Hopefully I'll get some free time this weekend.