I have a 92 Dakota 2wd with a stock 3.9. How much HP can I get from it, or would it be easier or cheaper to swap to a 318?

 

275-300hp no nos, +50 with spray on the 3.9l. but you'er going to pay through the nose to get that power. frame upgrades, trans upgrades, engine mounts, ect. look at the signature, i'm putting out 220 (actual dyno number) @ 5500rpm, and almost the same in torque.
good luck

 

You would be happier with a V8, and there are many more parts available for them.