Re: Help which cam
You can over cam a motor. Especially a 4wd. For a 4x4 you want low end torque. Generally speaking, the bigger the cam the higher the RPM. As for the Torker II manifold, it is designed for between 2500-6500 RPM, not ideal for a 4wd. The performer is designed for "off idal to 5500 RPM". If that is what you go with then use the perfomer cam. They are both designed to work together so you will get optimum performance that way. I would not excede 10:1 compression unless you want to buy the expensive gas to avoid detonation.
Those heads are from an 80-86 305, you are right about valves and cc. Those heads will supply your motor but the motor as a whole is too small for any real power so the most you will get out of high dollar machine work on those heads is about 15-20 hp, and that will probably raise the RPM range so you will hurt yourself more than help.
To my knowledge there are no 305 pistons that would acomodate 5.7" rods so I asume you have 5.565". Because of this I wouldn't run your motor higher than 5700 RPM I am going as far as using a rev limiter with my 383.