2.5 renix to 4.0 HO swap dash wiring, and fuel pump questions

[Billdozer]

Sorry if this topic has been beaten to death. Just have some questions I can't find specific answers to.

 

Currently have an 89 comanche with the 2.5 ax4 (4 speed manual). Previous owner put the 32 inch wheels from a 2016 wrangler on it. Looks nice, but is extra gutless. Has good compression, but pretty bad blow by.

 

Was planning on rebuilding it until I found a great deal on a 95 4.0 HO motor (150k miles) with an ax15 external slave. Came with intake and exhaust manifolds, wiring harness, radiator, mounts/brackets, throttle cable, ac compressor. Pretty much everything in the bay. 

 

I already have the transfer case input shaft taken care of. Main questions would be for the fuel pump, and instrument cluster. 

 

Can I just drop a 4.0 fuel pump in the assembly for the comanche? I know the previous owner replaced it some time ago (guage reads backwards)

 

For the instrument cluster/dash wiring harness, I found a 94 cherokee at a wrecking yard. Do I even need to swap out the dash wire harness?

 

The speedo is currently mechanical. What do I need to do to change that over to the electrical on the 94 instrument cluster? As I understand it, the current speedo won't fit into the HO cluster.

 

I know about the wiring from the XJ to rear on the MJ. Saw that great post about connecting them. Not too worried about that. Just what I need for the instrument cluster, and dash wiring.

 

Thanks for any advice/warnings, and sorry for any dumb questions!