how much lift can you use with stock vortec rocker arms ? i know the heads are about 475. thanks

 

there is no limit, there may be interferance problems with larger diameter springs used with higher lift cams

 

There's no such thing as "Vortec rockers". The rockers off of 96-99 trucks are the same garbage as any other stock self-aligning rockers.

Whatever the stock lift is, is already too much for them. They bend and give away several percent of the total available valve lift, even with weenie stock valve springs that you can squeeze open with your hand.