[Mike C]

The Longhorn already has 2 1/2" rear springs which helps. Not sure if all the brackets are same height as the 4x4 ones, but the other 2x4 trucks have 2 1/4" rears which make lift springs almost impossible for the back. The Longhorn frame is the same 40" width as the 4x4 trucks and not the 42.5" of the 2x4 trucks.

In the front you should be able to use spring mounts off a 4x4, just cut the rivets, and bolt onto your frame. I would tack weld the nuts to the bolts after torquing them down to act more like rivets. You will need the crossmember and braces from a 4x4 as well since the motor is mounted significantly further back in order to have a reasonable length and angle to the front driveshaft.

Sometime in the future I'll peer at my parts Longhorn frame and make sure all of the holes are already in it, but if not, they could be drilled pretty easily. Rear shackle hanger shouldn't be that much work.

A donor 4x4 truck seems the best (read fastest and most economical way) to do this. This would give you rear spring mounts as well if it turns out the 2x4 Longhorn front hangers are different than the 4x4 longbed hangers.