TBI swap scavenging list - experts inside, please

[BigBlocksRule]

I have an '86 single cab dually that I intend to use for a work truck until the wheels fall off. I'm swapping out the tired 454 and TH400 (both have been farm worked pretty hard) in favor of a fresh Gen 6 454 and 4L80E. A buddy is parting out an '87 longbed with a 305 in it. I've already snagged both saddle tanks with brackets, plumbing and switch/valve from that truck. My '86 was equipped with saddle tanks, so I'm hoping all the bolts for tanks, valve, etc. lines up. Next step is wiring and switch. How hard is it to follow these wires through the firewall and to the switch? I assume I'll have to locate a main power and ground wires, but are the rest of the wires pretty much bundled together?
My computer and wiring harness are from a '95 as is the 4L80E. Engine is out of that truck, so it will be much easier to scavenge the computer and wires. I'm counting on the guys at 454SS to help with chip/tune. Engine will have a 214/221 hydraulic roller cam which was recommended by Crane for good fuel economy and towing power. It's a bit more of a cam than the old "RV" cams we used to use, but I've been assured it's computer friendly.

While I have the donor truck handy, what else will I need for this conversion? I'd been thinking about doing it for awhile because I except for poor mileage from a tired engine and non-overdrive tranny, I really like the old single cab dually, but hung a stump when it came to pumps in tank and getting the wiring and valves to work for tank switching. Since the donor truck popped up, I decided to grab everything I could or would need off if it rather than having it all crushed.

Thanks in advance for the help!!!