I test fired the engine! It didn't want to start on the VW starter and just 12v, so I hooked two batteries in series and got 24v.
It started in one second!
I had been fighting it for like an hour trying various tricks adding a little oil, trying starting fluid, pumping the accel pump a lot/not a lot or rather opening the throttle 100% for "flood-clear" etc. Still fouled the plugs several times. Tried a set of brand new plugs, still fouled twice etc. Hooked up a battery charger (12v). Still no go.
In the end I gave up, connected two spare batteries directly to the starter and used a pistol-grip remote starter switch to feed the solenoid 24v as well (found out 12v wasn't enough to positively engage the starter ring gear as it cranks like a gorilla in 24v mode). The rest of the car was obviously still powered by 12v so the ignitors and everything else wouldn't fry. This did the trick. It started and ran great in one second flat! And it was repeatable.
Now the trick is to hook up two batteries in the car to a Ford fender mount solenoid so it's only 24v in starting mode, but reverts back to 12v the rest of the time. Oh, also need to feed the VW starter solenoid 24v on a second circuit because 12v just isn't enough. I'd also like to allow the secondary battery to receive a charge from the alternator while in 12v mode, but not in 24v mode. We've got a battery isolator and I have a couple of 40 amp automotive 12v relays to play with...