When you say you let it run hot, do you mean the engine overheated because of a problem with the cooling system?
I hope you didn’t just replace the engine without solving your overheating issue. That happened to me once. I was given a car that had recently had a rebuilt engine installed. The engine had to be replaced because it had overheated, but nobody could figure out why it had overheated. Eventually, I figured out the passages in the radiator had become clogged and a new radiator solved the problem, but it could have cost me the rebuilt engine in the process if I hadn’t been careful.
I have had a clogged catalytic converter, and while it did make the exhaust manifold glow at night, the temperature gauge never changed and the warning light never came on. Is the “check engine” light on?
[i]If you haven’t already done so, you need to find out why your old engine overheated before you blow another engine.[/i]