Thanks for a lot of good information and possible solutions.
As I stated, initially the engine would try to start, sputtering as long as the starter was cranking. Sometimes popping back through the intakes. Twice I got it to run when the starter was released but wouldn't increase in RPM.

When I discovered that the distributor advance bolt was only hand tight, I tried playing with that and considered the possibility that it might have been removed and reinstalled incorrectly.
As I played with the timing adjustment, I found I was no longer getting any attempt to start. I checked and I was getting a weak spark when I pulled a plug wire and connected a spare plug/grounded. Reset the distributor to #1 TDC (verified) top of compression stroke by observing valves). Varied timing within range, etc.. Still no start attempt at all. Not even a back fire.
This engine has a solid state distributor. with the coil inside the distributor (under the dist. cap), reluctor and ignition module under the cap as well. Cap is in good condition and appears as new, wires are fine also and in proper order. Plugs are as new and are resistor type (I think, they have an R in the number?)

I'm also wondering if there could be a problem now in the Mixer, as a result of the back fireing thru the intake valves, previously. The reason I raise this point, is, when I remove the LP gas line from the side of the mixer body and crank the engine over, I feel absolutely no vacuum even when I open the throttle. Is there something that could have been damaged or ruptured due the popping back thru the intake part of the system??

Steve