Reads like you have had lots of fun with Rangers.
4.0l SOHC might be worth something as is or with the new design timing chains and guides and valve/piston repairs.
Good read here on the bits and pieces: MudSlanger's Explorer 5.0 Swap In A 2000 Ford Ranger
'01 explorer will have type B PATS, '01 Ranger type E
Type B had a separate PATS module located above glove box/behind passenger airbag.
You will need to get that module and also swap the ignition key cylinder and door cylinders from donor, to satisfy PATS.
But you can also send the 5.0l computer(PCM) to a programmer and they can update the software and delete PATS requirement, so you can use existing keys and don't need the module.
But I think type type E had a starter interrupt, so you may need to jump the starter relay in the engine fuse box