318 dodge dart stumbles 5000rpm

when you installed the new electric fuel pump, did you also install a fuel pressure regulator? If not, you would definitely be flooding the carb.

I wouldn't send close to $200 for another 2bbl carb unless you know for sure the carb you have is junk. If you do decide to buy something else I would safe some money and upgrade to a 4bbl intake and carb, not too hard to find for relatively cheap second hand.

Maybe have a look in the for sale section or start a post about the parts you're looking for. Some great members here that will help you out any way they can.