I believe compression may be a reason it is difficult to start, but it is not the reason it isn't starting, it's a contributing factor.

As for "sputtering" it's fairly simple: one, maybe two or three, cylinders fired, and that was it. It didn't backfire through the carb or tail pipe. It was your #2, fired/tried to run. This is typical for this engine. Usual scenario is it will fire and run rough, then die. Then, difficult to start. Spray ether/starting fuel in the carb. Turn engine over and usually fires right up, but runs rough until warm. This time was different, in that it didn't fire after spraying ether in the carb.

As for your other questions, the original HEI was old. It was replaced with a brand new one. Timing was checked as matter of course in dealing with a new distributor.

Last edited by Woogeroo; 10/08/2018 7:04 AM. Reason: removed snark