Exhaust manifold angle?

[Chevy nutcase]

Gathering parts and pieces to very soon drop in a 8 to replace the 6 in my 66 c10 and manifolds are on my mind currently. My question to you fine folks is which type is best suited for these trucks? Outlet straight down or angled? Downpipes come in either version but to get around clutch linkage or any other clearance issues is my concern. Shift linkage isn't a a concern since this is a sm420 floor shift and will stay floor shift with a new a tremec TKX when the motor goes in.