[Dead Parrot]

The black plugs support the too much fuel issue. Not being able to turn the distributor suggests it didn't suddenly change time by rotating.

Since you know the jet/rod combo in the carb, check the manual. It should have a tuning chart. Possible the PO set things too rich. I don't see that causing the sudden no run issue but nice to know once you get it running again.

Turn the idle mix screws in until lightly snug and back out a half turn. Normal is 1.5 turns IIRC. Since it is too rich, this might help until the real problem is found. Just remember to return to normal once things are working.

Hate to think it but wondering if something in the timing gear/chain setup has come loose and let things move. Worked on a friend's car many years ago that suddenly wouldn't start. It almost would. Turned out the timing chain had enough miles that it had stretched enough to let it jump a couple of teeth on one of the timing gears.

Might pull and check the distributor gear. Some newer cams want a certain kind of distributor gear or bad juju happens. I haven't built one like that so maybe someone will chime in with better info.

With everything dry, try the following test. Choke full open. Don't pump it. Just drop a few drops of gas into each front barrel and then crank. It should fire or almost fire for a second or two.

Another thought is maybe something inside the distributor came loose.