The cars original suspension was light years ahead of everyone else at that time, it is fairly modern. Moving the upper shock mount from the upper control arm to the frame is a huge improvement. A front disc brake conversion would be a requirement from me. I would also update to the dual well master as well. A sway bar off a newer jeep will stiffen up he front end even more.

The Dakota option is a very good option (I have one under my 48 Plymouth coupe), it is a lot more work then adding a disc brake conversion, moving the shock mount, and updating the master. Depending on the condition of the brakes & suspension of the doner Dakota, your probably even money by time you rebuild the Dakota stuff.

If you keep the original frame, mount your 360 1 1/2" to 2" towards the passenger side off center. Keep the motor & trans in line with the frame, there is enough movement in the u joints to allow this. Then everything will clear the driver side exhaust. I usually put a notch in the crossmember to clear the crank pulleys, then box it back in. I've done 6 of these cars (5 39-48 Plymouth & 1 Dodge) 4 were original frames, 1 a Dakota clip, & 1 a full Dakota frame. 1 was just the disc brake upgrade & frame notch (360), 2 were disc brake & shock (318 & 360) 1 was disc brake, rack & pinion, sway bar (no shock move) (V6), 1 was a Dakota clip sold off before complete, and the current one is a complete Dakota frame. All of them got the master moved to the firewall. Gene