Considering magnum swap

OK, so right now I'm running a low compression mid 70's 440. It's got some get up and go, but its not a real power house, plus I think it's getting a little tired. Also, I'm sick of the fender well headers and I don't want to spend $600 on TTI's or Schumachers. And I'm tired of playing with timing and carb adjustments. Ideally I would love to find a 5.9 to swap in with an overdrive tranny. But at the moment, I may have an opportunity to get a 5.2 in a 2000 ram van 3500 for practically nothing. So delema number 1: does a late model over drive Trans fit in my tranny tunnel? 2: is the 5.2 that much less horsepower than the 5.9, should I just keep looking for a 5.9? 3: if I swapped in the 5.2, could I use the computer and wiring and replace it with a 5.9 down the road? And yes! I did check out magnumswap.com! Very cool site, super helpful! I'm sure a lot of u guys are running magnums and have a lot of experience with this, and I would love to here from someone running g a 5.2 magnum! Thanks in advance guys!