New crate 454

I've built and played with Chevy 454 engines for decades — both performance and towing. There is absolutely no way that a new engine should over heat due to "new engine friction" or choice of lubricants. Were that the case, it would not last but a few minutes. I can't guess what is causing your problem, but it's not friction. Your new crate motor should have ceramic rings that require no break-in. Timing can be an issue, but 4 or 8 degrees should not make a huge difference. Running lean will show up on the spark plugs. Beware of your carburetor rebuild and what was done with the metering rods and the secondary air valve on the Q-Jet (an excellent carb). Unless the serpentine system can change the pump rotation, long and short pumps are the same except for spacing to the radiator. The long pump will have space between it and the block. I've never heard of an HD pump — and I've used both after market as well as OEM pumps (latter are nicely powder coated). There are many variables in your description — but I am suspecting radiator/fan operation (though the temps you mention are so extreme as to make me wonder about the sending unit). That's the one in the head — easy to change. BTW, the only time I ever heard of a problem like this was with a new Pontiac. After many trips to the dealer it was finally discovered that the new vehicle had come without a radiator shroud! Oh, and I do know of a 454 that arrived new with a restrictor dropped into a water passage — hell of a time diagnosing that one. And it was clearly deliberate in the manufacturing process.