Dumb question maybe, but are you absolutely certain that you don't have the new distributors 180 degrees off now? Maybe that's why it will only fire once you turn it 40 degrees...
That does not matter, it would never even start if it's more than 45° off (1 whole cylinder).
I would not tear the engine apart. You can easily verify TDC on the damper with a simple piston stop. If the damper is wrong, my guess is the ring slipped. You already verified the cam timing gears are on correctly. Plus it ran good before, and that is nearly impossible to change unless it jumped a tooth or the chain is somehow damaged, or one of the woodruff keys broke. But you already verified all that is O.K., right? So what has changed? The distributor, or the EFI. You have tried a couple different distributors, and nothing gets any better. You did change some settings in the EFI, I guess? That would be the 1st place I'd look at very carefully.
