Hopefully it was a manual transmission car, unless you are going to transplant the transmission too. That takes some significant work to do. If not, from what I've been hearing, the 5.7 computers don't like not having their transmission signals missing. And, as mentioned above, you will have no power steering unless you go Alterkation or something along those lines.
You are talking about a high dollar swap either way, even if you do most of the work yourself. It gets done all the time, but there's a learning curve and some parts of it are pretty steep.
That's why I went with the 5.9 Magnum w/EFI. That was a learning experience too. A few years later, I'm stroking the motor to 408", adding an automatic overdrive, upgrading the suspension and brakes even more, adding 3.91 gears, upgrading the seats and adding even more chassis stiffening. It runs, drives and handles like a dream now, but at less than 3000 lbs with only 275 to 300 hp , 3.23's and a non-lock-up 727. It just isn't fast enough....yet. I believe it's only in the mid 13's set up like this, but not for long.
Your 5.7 should be a rocket with the factory EFI with the right ECM and a good re-flashed tune.
