Fixing vs. Buying a New Engine / 273

Totally forgot to mention. I currently have an open 7 1/4 rear end with 2.94 gears and 10" drums; however, I've got an A-body 8 3/4 with an open 489 cased 2.76 gears that needs shock plates and U-bolts. In the long run I'd like a corner carver or pro-touring type of car. Right now I'm cruising it because all I have is sbp 14" steelies and 205/70/14. I know once I go to a bigger engine, wheels and tires may have to go. I've also got a floor-shift stock 904 in there.

If I do swap the 273, I was thinking about still keeping it in the garage and using it in the future to practice or teach myself engine building. Make it a little mini-project/scavenger hunt for used performance parts sort of ordeal.

I guess the question is, "Is it worth putting the $300 or so into an engine that isn't that desirable?" I know for a fact I don't want the 273 to permanently reside in the Dart.
with that being said grab that 340