1973 CB 750 engine into a 1976 frame?

I have decided to attempt to nurse a 1976 CB750 basket case back to life. I have a 1976 engine, but the more I look into it the more I wonder if it's worth dumping money into to get running.
A friend of a friend dumped their 73, was thinking of buying the engine.
How interchangeable are they?
Is there a place to find out what parts are interchangeable?
I'm new to this (hence my profile name).
Cheers!

all knowledge sohc and your swap is do able

http://forums.sohc4.net/

Thanks!