Re: 97 4.2 2wd
Once you get a V8, and a 12V would be the more common one to find, and less than half the price of a 32V unit. You'd have to factor in mounting points for the block. The V8 will also need a wiring harness (as mentioned) along with a proper PCM as the V6 PCM won't be compatible. Total used parts will be in the $3-6K range depending on condition. A 32V block would be about $3-4K alone, in fair condition if you can even find one used.
You'd also need the transmission as the V6 trans won't be able to handle the torque capacity of the V8 and thus won't last long. That's providing that the bellhousings match up, which I doubt they will. Tack on another $1-3K for the transmission. Then it comes down to getting the drive shaft, which now it more than likely won't fit so you'll either have to go custom ($1K or so depending on type of metal used) and the time just doesn't add up....
For $8K, you can put down on a new 32V 4.6L truck that's ready to roll and last you a few years of payments, not including the down payment you'll get from your '97.
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!