im building a 350 and cant decice on push rod length. do i use stock or will it need to be changed. heres my specs

350-bored .040
vortec heads .600 springs screw in studs with guide plates
cam is comp xfi 268, .570/.565

if anyone can help out that would be awesome

 

There are too many variables that you don't have listed and even then it would be a guess that I wouldn't want to risk. Just buy a pushrod length checking tool and then you can trust that you did the job right and no worries about bent pushrods, broken rockers, etc.

 

If you're changing anything that adjusts the lift of the pushrods or valves, you need to check for proper length. You might be able to reuse them, but you won't know until you get the stuff installed and can check it. Read up: http://www.carcraft.com/techarticles...h/viewall.html
While that is by no means all inclusive, it will help. There are other threads on this site where some experts and pros discuss the right and wrong ways to do it. If all else fails, ask a question.