Too bad I didn't catch this thread earlier. I am doing an almost identical swap into my '71. And, we're about to the same stage. Mine's driveable but the wiring isn't 100% done. There's one difference I'm glad of, though: my donor was a '92 Caprice cop car so my VSS has both the electric and mechanical sending units at the transmission. I can hook up a speedo cable to my factory speedo but I'm installing a full set of Autometer gauges in my dash so I'll be going with an Autometer electric speedo when I get to that point.
Right now, my biggest hurdles are: TCC wired into my brake switch, ALDL/SES wiring and the gauges, which are important but sort of separate from the swap itself.
Don't know if it's the right thing to do or not, but I just left the A.I.R. pump installed in the serpentine setup with nothing connected to it. I'm running headers so hooking up the lines was out of the question, anyway.
I'm running a carb-style air filter with the IAT temperature sensor mounted to the base plate. I had to use a 1" spacer on top of the TBI spacer for clearance of the coil but I have no issues with the wiring since it still uses the factory spacer underneath the aftermarket one.
I also used the factory wiring harness. I de-loomed everything and spent many hours (I'm no EE but wish I was!) isolating and removing circuits I didn't want/need. That hardened gel GM used at the bulkhead connector was a particular PITA. I used a heat gun to soften it and scraped it all off with a utility knife. As I recall, the circuits/sensors I left in place were: O2 sensor, CTS, knock sensor, IAC, IAT, TPS, oil pressure, TCC, VSS and A/C.
I called up Brian at tbichips.com and had him custom burn me a chip for my 6965 (the same ECM you've got). I told him exactly what I was keeping and eliminating (smog stuff, mostly) and he burned me a chip with a little hotter than stock specs but I already had "cop car," specs to begin with so he cautioned me it wouldn't be a huge performance gain. But, then again, even the 9C1 police optioned Caprices were only factory rated at 205 hp!
I re-loomed everything I had left with a Summit wire loom kit (pretty cheap and looks great) then fabbed my own (probably not weatherproof) bulkhead seal. When I'm all finished, I'll probably silicone over the wires passing through the bulkhead.
So, if you don't mind since you seem to have expert advise, I'd like to ask what is the function of the VSS module located in the dash cluster in about the center of the Caprice? That's something I didn't realize was there until after I'd gotten rid of the car and one of the wires coming off the VSS is supposed to connect to it. Did it have anything to do with cruise control? Does it serve an important function and do I need to go source one from a JY or can I eliminate that wire? As I recall, there were 3 wires coming off that VSS and the other two are connected to their proper places.
Finally, my old fuse panel only has about 8 or 9 glass fuses and one spade terminal for an unfused ignition hot source. Oh, and one or two spade terminals for constant battery power. I've already wired 3 different EFI-related circuits (with correct-amperage in-line fuses) to these terminals and I still have a couple more circuits that require ignition-hot voltage. Is there a clean way to build a separate fuse panel or buss bar that provides ignition-hot voltage? Maybe a supplemental fuse panel or something? I've checked vendors who specialize in hot rod electrical and haven't found what I'm looking for.