I agree with the above. First, make a plan, and if your plan is to flip it when you’re done, stick with a small block. The big block swap will easily out price any machine work on the 273 you have. And that’s not counting all of the u seen upgrades that the big block will require, such as that mystery rear end, which I suspect is the original 7 1/4”. Around here (SE Michigan) you can have the matching done on the 273 for less than $2k, and all in, meaning having them assemble the long block for you, at under $3k. You would still have to do the final assembly, paint and reinstall, which I believe you can handle. You start getting away from the 273, and needed parts to do that quickly add up. Unforeseen things to even do a 318 would be a different trans and torque converter, which are specific to the 273. My advise is to slow your roll a bit, gather information, and proceed slowly, bring your first foray into the Mopar world.
Welcome to FABO by the way, the best place to be for a Mopar young gun.
