Unless you have some insane 460 in there with 1000hp+, you should be able to cool it. Changing the engine because you have a cooling issue is like killing flies with a shotgun, it's way overkill for the issue. I have a 750HP, 520" FE and after some initial cooling issues I got it under control. As 40K Later mentioned above, I have a Fluidyne radiator as well. That, coupled with a proper thermostat, a proper tune, and the highest flow puller fan you can fit in there, and perhaps most importantly a very tightly sealed shroud, should take care of all but the most extreme engines. The highest flow fans I have heard about come from Ford Taurus and Lincoln Mark 8 cars. They move an extreme amount of air. You can buy them new with a shroud for a fairly reasonsnble price on RockAuto and other places. You can also look in junkyards but I've read that because the fans are so popular most are already picked clean out there.
It would absolutely be cheaper and easier to fix your cooling problem than to swap engines. You're looking at welding in new engine mounts, a new bellhousing, getting new headers fabbed up, and a myriad of other issues in an engine swap such as this. That's a ton more work and money than a radiator and fan swap and a tune. In my case I didn't have room behind the radiator for the Taurus fan. I have a custom aluminum shroud that I had built and a Spal fan and it works. I had all that completed just as the worst heat of the Houston summer had passed, but so far it's working well for me. Once the heat of the Houston summer hits next year, if the Spal doesn't cut it, I'm going to go with one of these:
https://deltapag.com/ I have every confidence that I have my issue licked, but if not the delta pag fan will be the final bolt in step in the process.
I understand your frustration with the cooling issue. At times it can be frustrating to the point of resignation, which seems to be where you're ay now. I get it. However, the right combo of radiator, fan and tune can cure almost all but the most extreme issues. Big fan, proper thermostat, correct tune, big radiator and a very well sealed shroud can cure almost all cooling ills. Your engine swap proposal is difficult and costly, the proper cooling system mods as outlined here are multiples easier and cheaper. Good luck!