The fact it won't even roll in neutral has me believing it has nothing to do with oil pressure or the hondamatic unit. The first 2 areas I would check if it were mine would be the sub-transmission (the part that determines F-N-R, this is separate from the hondamatic), and the front and rear diffs. Make sure it is in N and 2wd, jack up all 4 tires, and see if any spin.
If you change the primary shifter positions while running, can you hear or feel it shift from N to F, F to N, and N to R? Report back after checking all that.