on the Diamante 3.0 , be aware that that engine has different cams(cam timing) and has interference pistons that give it that 10:1 compression. The Diamante engine might not work to well with your ECU.
The caravan engine uses the same cams as your stock engine, but it will has cheap stamped steel cam gears. One way to tell if you really have a Chrys. engine is looking at the cam gears.
And the Hyundai engine is from a bunch of RWD configured Montero engines that Mitsu sold off to startup Hyundai company. It is already drilled, tapped for motor mounts and the dipstick hole is the same as a Montero.
I'd do the diesel if I had the means. The 3.0 is a pretty dependable family truckster engine, but mods are fun...