The story continues...
Confirmed last week with the PO that he was pretty sure did not install the metal cap on the front CCT about 19k miles ago. Let that serve as a lesson to all - use the cap or your rubber shall explode and the engine could become pregnant.
Today I drained the oil, took off the exhaust, cleaned out a few rubber bits from the sump, sealed it back up, filled the oil, replaced the front CCT (now with cap!), and meticulously put everything back together. Turned the crank a couple of times using the access hole (where I'd also set to TDC on 3 (rear) and 1 (front) to be safe) and all seemed good. Double checked all the connections and vacuum hoses just to be sure.
Once all was reassembled I hit the starter and got a colossal rattle for about 3-5 revolutions of the crank. Cycled the ignition and tried again, and now it will turn over just fine (sounds totally normal) but does not fire. No FI light, kill switch on, neutral, stand up/down doesn't make a difference. Fuel pump primes fine.
Any ideas? Timing issue? Those who have replaced CCTs have there been any untoward noises the first time you've fired it up?