Originally Posted by MotoJ
A 9 out of 10 time machine sounds perfect to me. Hacks are a lot of fun, but you should be aware of the consequences.
Just the empty car will be a lot of stress on that bike. A subframe might save the frame from twisting, but the swingarm, forks, steering head, shock mounts, etc. are all likely to get some tweaking. The wheel bearings will take a lot of abuse too.
At the least, I'd save that OEM exhaust and buy a cheapo MAC 4 into 1. Those originals are almost unobtainium nowadays. You could probably sell it to the right person and buy a whole other bike.
Whatever you do, post lots of pics!
I do have a 2nd CB550F in pieces and have a spare OEM exhaust in the rafters. A bit scuffed up but decent for 30+ years old.