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I would question the wisdom of any larger than .360" lift cam in a stock head, the flow just isn't there. You may be surprised at how quickly (lift wise) these heads stop flowing with even the best port jobs. 
My experience is that long duration cams (over 250 @ .040) makes a sloppy around-town ride with even a 10:1 motor. They have lots of power when turned at big rpm, but suck riding between stop lights.
It's all a compromise, so target for your personal fun zone.
My CB 750 K6-77 have a ported cylinder head which gave a huge difference.
This was the first meaure when modifying the CB750's here in Sweden during the 70's and first half of 80's
Together with more modifications, the most common ones I suppose
RC 836cc pistons adapted to the chambers of the ported head.
Later replaced by stock Actions Fours 836cc pistons (with less compression) when the RC's got burned.
Cam: Action Fours SS-1, which I have plans to replace with a RC 315 replica, a hotter cam when the SS-1 is very moderate.(Lift: .360 , duration: 270 )
F2 inlet valves and new springs.
Lightened alternator
The engine is night and day compared with an original CB750 .. and the sound too !!
I have had my CB 750 in a barn since 1990 and I have found a lot of goodies for my bike which will get a huge overhaul starting this winter.
Nice too see that a lot of people still like the CB750 and in the way I liked it from 1979 to mid 80's.!
I have also found a Yoshimura 4-1 replica, which I gave up to purchase for long time ago. Order next week if in stock.
There is a lot of goodies to order from US.
Here is a nice link for the old cams and other CB750 stuff.
http://www.satanicmechanic.org/index.shtml
