I ran 3/8 aluminum hard fuel lines from the tank thru the fuel pump all the way up the firewall and into the back of a dual hard line feed to a 950 cfm Holley. Ran a 1/2 thick thermal spacer under the carb - no issues.
I still think you cant do this with a mechanical pump.
Prove me wrong, I hope you can.
You may be right. My new regulator will be here Wednesday so I will try it before i go with electric pump. I also have a 1/2 im phenolic spacer under the carb.