I bought this awhile back and finally got the car in the shop to work on it. This is the Summit brass/copper heater core similar to the one I put in the 1970. Same manufacture. See https://www.summitracing.com/parts/sum-382140/overview/ Says it fits 63 to 68 Non AC. They did not offer one for AC at the time. After looking at pictures it appears to be the same so I ordered it. With the old one out for comparison it is very close. See below: They now carry a copper one specified for AC cars: Spectra Premium Heater Cores 94539 The upper nipple on the old one has a slight bend to it. We'll see if it is really necessary. The Spectra has the bend.
Follow-up: Just to document, the straight upper hose connection gave me the extra clearance for the 455 valve cover I was looking for, BUT I did have to notch the firewall hole for it to clear without rubbing. The bigger issues will be the lower connection which will require a 90 degree bend to bring the hose out from behind the head. I think a hose with the bend cut close to the firewall will work, I just need to remember to put it on before the engine goes in!
