[P.S.]

It started with a random miss and gradually got worse. Hmm.. I'm no expert on motors, however, I do know a lot about electricity.

The plugs were wet with fuel- No fuel starvation problem.
The spark is strong and blue- No coil/condenser problem.
Compression is good- Not a valve problem.

A possibility is to look for cracks in the distributor upper housing (the thing that the spark plug straps go to) and the dist. cap. Look for signs of arcing inside the bakelite parts. Had this happen on mine when I first bought it. Drove me nuts trying to figure it out. Same symptoms as you describe. As the arcing continued, it left carbon, which caused more arcing, which made more carbon, etc. Finally, the car barely ran. Replaced the dist. housing and it ran perfect again.