In my opinion one would go to a 12 port for is looks and ego appeal. At 2500 to 3000 RPM driving a street rod on a rod run it would make little difference. People and street rodders do things because they want to not because they need to.
If I was building a street rod I'd use a 270 GMC because in 1953 no one had heard about a 302 and they make approximately the same torque which is what pushes you down the road. I'd also use a small port head because of it's velocity when the valve opens and it's would have no stumbling when starting and who needs 5000 RPM. Even tho gaskets are better there always some problems with aluminum to cast iron especially with long inline engines.
If it's a 12 port GMC you are looking for you can contact the Fergusons in Wilmington Ca. they have most of the patterns for the various GMC 12 ports and Joe Fontana has a few Skinners available. Most of these were designed for racing so intakes are not to choicey
It's always a choice; sometimes it's money and like I said "EGO" plays a part....Good luck and have fun with what you are wanting to do..................
