i owned a 1988 GSXR1100J that had that front end and i have had that bike well over 140MPH, don't know if i would trust an old Honda front end at those speeds...
I have regularly Mick, and in a straight line they're fine. Post Classic racers are restricted to OEM or forks that were available "back in the day", so mostly spindly 35mm forks, hence the amount of frame bracing required to make them go around corners at speed.
With decent forks and rear suspension though, (not to mention taper roller steering head bearings, bronze swing arm bushes, good modern tyres etc) you don't need much in the way of frame bracing to make old CB750's handle quite well.
I really was surprised at how well my gold K2 handled, Ken Piper, the original builder really got that fork geometry right, it went around corners like a modern bike. Cheers, Terry.