The majority of chevy tri power setups that i am seeing seem to fit up to 86. I have an early 90s chevy 350 with a 600 holley. I would like something more visually impressive. How difficult would it be modify these earlier manifolds to fit ? The manifold center bolts are vertical on my motor. Is it just the bolts that are the issue ? Or does it include the port size as well ? Or anything else? Thanks in advance. Obviously changing heads would allow the use of the earlier manifold. Want to work with what i have right now.