I think the $$$numbers have gotten closer together on all the more NORMAL ohv engines--not hemis or nailhead-- we actually use very few OEM parts anymore except for the core block--most companies that do after market parts--cams,heads,manifolds, ignitions are fairly even priced on there stuff---

So--if you are talking about a strker kit type motor with a set of alum heads, cam and lifters plus a carb manifold---your biggest $$$differance will probably come come the parts needed to install it in your particular car--mounts, accessory drives, exhaust, etc