Help opinion's needed!!!

kdog said
Ok if I use a Offy from ebay what's the advantage to a long runner vs the shorter manifolds

Not sure what you mean here. Offy's are basically a short runner manifold - similar in size to to a stock 1 barrel or stock 2 barrel. Long runner manifolds include the Aussie manifold and original and reproduction Hyperpaks.

kdog said
and also what is a good carb to use Donnie

For the street, the 390 Holley seems to be the one everyone uses. With a properly build slant for racing, a 600 I've seen mentioned.