I have done this exact swap, in a 91 no less, any 92 or later dakota or durango 5.2 or 5.9 oil pan will work just fine. Some of the late vans after about 2000 used the skinny rear sump, rams earlier vans and jeeps used the one that wants to sit on the frame and steering... If you use that pan you can use the good one piece magnum gasket. Do not swap the rear main cap, it wil eat up your engine quickly unless you line bore and hone the block. You will also need the oil pick up tube.

The TBI ran great on the original 318 but would not run right on the magnum, Idle was about the only good thing it did. This was with the eddy intake and adapter on and big single exhaust and the 92 93 ex manifolds. I think the 318 TBI engine had 180 HP and the magnum was 235 so it just is not right. We eventually swapped in a 93 intake/harness/computer/fuel pimp and it ran awesome and yes there were a few wires to swap but no biggie.

I have done this swap and am telling you the way to do it with as little headache as possible.

The eddy intake bolted on with no issues whatsoever, hopefully the knock off you got is better, check the port line up also as it was way small on the cheap intake.

A carb swap with the correct intake is a breeze also and you can use the TBI fuel pump and return system with a cheap regulator and a 650 is no where near too big for this motor. Again I have done exactly that. I have done quite a few very similar swaps to this but I gues I should stay off your post. Sorry I tried to help.