ALL around "guru" needed for advice

[bulldawg2]

I recently purchased a 70 Stepside, 250, manual. The truck is pretty much unmolested, with the standard accessories- drum brakes all around, no ps, no a/c- just a basic 6 cylinder truck.

I am going to do a frame off complete rebuild over the next 6 months. My plan is to drive it for a few months, while I work out the kinks of disc brakes, p/s, and a few other things- all the while plannng and buying for the final "build". I have a 72 crossmember that I have rebuilt to roll under the front end for the disc brake upgrade.

My first question- what is the difference in the fuel lines between the v8 truck and the 6? I know that the 6 cylinder truck came with BOTH 3/8 and 5/16 2 piece fuel lines from the tank to the pump. The v8 ALSO came with both. Also, I knwo that the tank float is different between the 6 and v8. THAT I do not understand- esp the different tank floats being different for the 6 and the 8- though the tanks are the same size. Also- the factory tach- what is the difference between the 6 and v8 tach other than maybe the 5k and 8k on the face? Will an 8K factory tach connect to my already upgraded HEI distributor- and work as desired until I drop the v8 in it?

Also, I am going to put an sbc crate motor in it. I will keep it staight shift- and I already have a Tremec 500 to be installed. The 250 has the casted holes to connect the clutch linkage. You guys that have done the v8 upgrade and stayed with a straight shift truck- do I need a Gen1, Gen2- what block am I looking for?

Thanks in advance for the advice!