Led Headight Question

Question for you. Why couldnt a guy take the 7 inch housing from a late model Jeep Wrangler with a good set of quality bulbs and put it in their A body?

You could, with socket adaptors, but those headlamps suck. They're pretty to look at, but their performance is the pits. A substantial amount of the food in my fridge is there because '07-'17 Wrangler owners rightly hate trying to drive at night with the stock headlamps.

Surely that has to be better than the old sealed ones

Don't bet!

and much cheaper than 500 bucks in lights?

There are plenty of good options for upgrade headlamps that don't cost a pile of money. If all you want is cheap and decent, the only sealed beam worth using is this one. If what you want is cheap and decent replaceable-bulb, that's this one with these bulbs and a good relay harness and careful aim job (that part's important no matter what lamps you have).