There were issues with first Gen 7 bolt engines only related to DSM stuff for some reason (something to do with manufacturing - well documented on tuner forums) Starion/Conquest is an option but as dash has pointed out you will need both engine + transmission due to 4G54's being a wide block mounting pattern. If you go for 4G63 turbo transplant you will need to add a tuffpan/reinforced sump plate on the gearbox. Once you start heading 250+ hp the transmission housing will start to flex and the gear sets will no longer mesh together properly under the increased torque (boom, broken teeth...) The reinforced sump plate will allow the standard KM132 to hold 500+ hp which will be plain scary in a lightweight truck. An early Evo (1-3) or a Galant VR4 engine is a 1 G 6 bolt engine and are literally bomb proof. A big power increase will need a high load pressure plate to prevent clutch slip. The clutch cable mechanism can cause the firewall to flex enough for the metal to tear with a higher rated pressure plate and will need additional reinforcing. Mitsubishi small trucks are a flexible platform with lots of cross compatibility between model generations and engine swaps but it's still a truck and has limitations.

*What I'd recommend - swap the front steering hubs and brakes from a Gen 2 truck. Vented discs and uprated calipers - cheap and easy, straight nut and bolt swap. Compare your front stabiliser bar to a Gen 2. If your truck has the thinner stabiliser, swap the bar and all of the mounting hardware from a Gen 2 truck - again cheap and easy. Consider the 38DGES swap. There is a bit to it. Main things you will need is the adapter kit and an electric fuel pump (HVLP - high volume, low pressure) Follow the guides on the forum and you can't go wrong. Bigger exhaust and headers if you can get a set. The key to the G63B to making power is getting it to breathe. Next is de-governing the engine. The water pump driven radiator fan and the balance shafts add significant weight to the rotating masses the crank has to expend energy on. Delete the shafts and add an electric thermo cooling fan and you'll get a much improved throttle response. Added bonus, the electric fan is much more efficient at keeping your engine cool and frees up precious engine bay space, takes a load off the water pump bearings and makes it easier to get to belts and general access for repairs/servicing.