i'm getting ready to build a mild 360 for my 62 dart for use while i collect parts and develop plans for her original polyhead. i'm trying to build a respectable 360 walking the fence between efficiency and performance so i can actually afford to drive the thing. i've got an la 360, offy dual port (not dual plane) intake, and i want to use 1 5/8" primary headers w/ 2.5" collectors, 2.25" dual exhaust, mp purple power 260 cam, and a holley 600cfm carb. i'm sticking with ported stock heads, stock 1:5 rockers, and stock valves. sounds fine to me, but the guy i got the offy from said that i need to contact offenhauser and ask them what "application" their intake is designed for (ie: how to build my 360). i already know that i need to use four hole gaskets/spacer (or just keep primaries isolated from secondaries at least) and i'm told a vacuum secondary carb in order to utilize it's intended design advantages. does anybody else know of any special requirements or preferences these manifolds like?