If your Holley 450 cfm is a spreadbore carb, Offy sells a spreadbore -to -squarebore adapter. I got one at the local hot rod shop. It adds about an inch of overall carb/manifold height, but that shouldn't be a problem.
I/I #4101
'71 GMC Jimmy 350, sm465, np205,3.73 posi.
'68 C/10 Stepside 292 (.030 over) Offy Intake, 500 CFM AFB,Clif headers, sm465, 3.73 posi.
'67 K/10 454 project.
'72 K/5 rolling frame project.
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