[b-man]

GPG38AS is what I have in my 1964 convertible Le Mans with factory air conditioning. I’m using a 1966 style radiator with the drivers side upper inlet hose.

This is the Cold Case Super Duty aluminum radiator with twin 1-1/4” tubes, their other radiators have twin 1” tubes.

Best to call and speak with one of their sales people and be sure you get the proper one, the part number I listed above is for an automatic transmission car. Be sure to ask about the Super Duty radiator with the 1-1/4” tubes.

https://www.coldcaseradiators.com/pr...8aAtjaEALw_wcB

[Baron Von Zeppelin]

Verify if the builder used 160* or 180* or 195* thermostat.
I always use a 160* in all my old cars , and drill a 1/8" hole in the outer rim of the tstat as a "burp" relief to prevent any trapped air when refilling the cooling system.

And be sure to run 93 octane , preferably with some lead additive.