70 pin Cat converted to 40 pin

I have a 2000 KW W900 that I am working on that a friend purchased that had a 3406E 2WS Cat in it with a hole from 1 side to the other in the block. Anyways he bought a 3406E 1LW complete engine that was just overhauled aprox 300,000 miles ago. I opened it up, put new bearings in it anyway, checked everything out & yes it was done recently and correctly. But the 1LW is a 40 pin engine where as the truck is wired for a 70 pin ECM. I had him purchase a new 40 pin connector that I am removing the pins from the 70 pin connector and pinning the terminals into the 40 P connector per the diagram ( have diagrams of both a 40 & 70 pin) but I am needing some help as to what I do about a few things as do I splice both the unswitched + to put into cavity 4, splce both grounds to put in cavity 5 on the 40 pin ? Then what about my inputs for pto, outputs for pto, outputs #6,#7 from the 70 pin where as the 40 pin has cavities for multi function inputs #1 thru 3 & outputs #1 thru 4, #4 says for cooling fan for modules july 96 & earlier? What about wiring in for a fan override relay ? Yes I there are companies that make an adapter but I want to do this myself. Thanks for any info