ive got a 70 vintage block with a old school firing order and its in a 89 notch i have a 90 gt harness and the inj are firing at the wrong time so im going to change cam to a ho cam my question is can i use rollor lifters out of a ho motor and push rods out of a ho because i have them on my bench and it would save me money if i just bought a cam

 

nope, you'd need retrofit roller lifters - but you can just buy a flat tappet cam for a 351 and stick it in there, it has the later 302 firing order.