Compression checked today.
Engine cold, all plugs removed, throttle and choke propped open

#1 - 165 psi #2 - 170 psi
#3 - 160 psi #4 - 170 psi
#5 - 170 psi #6 - 165 psi
#7 - 170 psi #8 - 165 psi

#3 is a bit lower than the others. Rechecked it and got the same number.

Cranked engine over with all plugs removed to look and listen for any signs of something that could be causing the vibration. I was under the car on the lift. Nothing noticed.

Plugs look OK to me. I don't see any sign of fouling, misfire, damage, or detonation. Not the best pictures I know.

Removed valve covers to take a look. Clean inside, no obvious damage to anything. All valves move as expected when cranking the engine over. I did not try to measure lift.

I'm about ready to rule out a misfire as the source of the vibration. I've ruled out the torque converter or flex plate since those have been replaced. I am pretty sure that vibration is so great that the motor and transmission mounts cannot dampen it out. I do plan to investigate the transmission mount a little further before I rule the mounts out. Nothing from the engine or trans is hitting anything on the body of the car. The front frame rails and inner fenders are original and were in good shape. I did replace the cowl, firewall, and all the floors. The torsion bar mount is original and was in good shape.

I'm narrowing down the possibilities to something internal in the engine. I did not check the transmission to engine alignment when I put the car together. Both dowel pins in the block are in place and the engine and trans are matching numbers, so I assumed it must be right. To measure the alignment, I think I would need to disassemble the trans so I could bolt up the empty case and use a dial indicator to measure the alignment. This is quickly becoming a major job.

John