Back when I would pay someone to do that, there was (still is, I think) a guy I used on Ebay named something like CookMike222 in SoCal who did both the harness rework and the initial PCM re-program for my Falcon's engine. His price was very good (way better than those mentioned above, like less than 50%), as was the work he did. You just have to ship him your junk in a box, with a list of your parameters.

If you know somebody with HPTuners, you can do a basic reprogram in like 15 minutes or less. People have made careers out of this . . .

I'm using a GM harness for one of their crate engines on my custom Gen IV LSA-like engine in my '66 Chevelle. GM sells one specifically for their LSA crate engine. It hooks up to all of the sensors and requires only ground, switched and unswitched +12VDC. It has relayed outputs for fans and a fuel pump. Definitely go with the VaporWorx fuel system that CarlC recommended. That harness and fuel system have been completely reliable for me for years now and I highly recommend them!