As far as I know, the winning SOHC CB750 cam chain combo is:
(and you can buy most if not all of this stuff from APE, the sponsor of this performance forum
LINK)
1) Tsubaki HD endless cam chain
2) M3 Racing cam chain tensioner/slider (replaces lower rollers)
(
LINK)
3) modifying the tensioner or replacing with a manually adjustable one
4) possibly adding an adjustable top cam gear.
A well built CB750 motor should not have any cam chain problems at all. Buying all these items new should cost around $285 with shipping
Cheers,
Fang