The OFFY is easy to find and less $ and you can bolt it up with stock exhaust, but (unless you want to run multiple rochesters)they only come set up for a 4bbl carb so will have make an adaptor plate to run the 2 bbl. You can also just buy an adapter and run a 2bbl on you stock manifold, Langdon's has the adapter, carb(the holley/weber) and the linkage.
