57 Chevy,
The reason you need self aligning rockers is due to the pushrod holes in the head.The vortec are larger unlike the early design which utilized the heads small hole to keep every thing lined up.The self aligning have a slot in the valve end that keeps the rocker from sliding off the valve. Just by a set of stock rockers they will work just fine.You can run a stock length pushrod I only recommend if are planning to race or rev the crap out of it (6500 rpm) buy a set that are at least carbonitrited (hardened).All in all the vortec head will out flow any stock head and better yet spend the money and buy a head with at least 200cc intake runners.Remember you can build compression but if you can't get the air flow it won't gain you a thing.

In the works 2006 GEN III 6.0 /4L80E/ 205 New process,A/C and power brakes .