Hank that second link on the 450 is not a DP it is just a Mech. secondray carb with a transfur tube like any Vac secondary 600 holley. That is the same 450/s I run.And to used this carb with a turbo hat You need to change the bowls on it and do away with the transfur tube and put Dual feed bowls on it.And you use The metering block off a 390 carb for the rear.I have talked with Holley on this matter,That is how I know you can use the 390 metering block.
Larry/Twisted6 [oooooo] Adding CFM adds boost God doesn't like ugly.