[RocktimusPryme]

I think you are over complicating it a bit.

I’m going to give you some generalities here but by and large they will be correct.

I don’t think Pontiacs are notably worse than any other major muscle car brands as far as cooling.

This has been talked about here before but the BIG caveat to cooling is radiator surface area. 60s cars tend to be undersized in the radiator department. I’ll post a picture I have from a video I’m editing for an electric fan swap on my 67 talking about how much bigger radiators started getting in the 70s and going forward. So a 60s car is almost certainly going to be harder to keep cool if you have a big engine in it. Not impossible, you just have to work harder with the radiator in a first gen bird compared to a second gen.

Related, yes different models were offered with smaller/larger rads depending on if they were AC or by engine size. I think often people swap big engines and aftermarket AC into cars that came with an 326 and no AC, then are shocked when it won’t stay cool. Other tricks too, extra baffling, bigger fans, smaller water pump pulleys etc. All the makes did that though. Not Pontiac specific.

If you want a Pontiac specific problem it’s that there is sometimes too big of a gap between the WP blade and the backing plate. Easy fix though. Some have reported that can make a giant difference. Going to the “ac” pulley setup did help me. Some people say there is a difference between the stamped and cast WP impellers. But others say there isn’t. So I wouldn’t put that one high up in the pecking order.

In short later cars are going to be easier to keep cool than early cars especially if you have a powerful big engine. Other than that, if you want to keep it simple, big clutch fan and a shroud and you will be fine most of the time. There is also a huge flex fan that some people swear by. I’m sure it works, just can’t stomach the power is sure it eats.

Electric fans are great, there is a reason the OEMS use them now. But there are always tons of pitfalls and ways to do it wrong. I would try the simple and cheap answer first with a big mechanical fan.