Well, I think I have it licked with no small part going to the helpful suggestions here. Whoever did the previous top end replacement left out the gasket, perhaps to increase the compression?*** In any event, that left the impulse port in the base of the cylinder flat against the deck of the crankcase. There was no air whatsoever moving through the impulse channel in the cylinder (confirmed with mouth suction and some hose). Luckily, my meager Husky box o' parts had a gasket for the 55. I put it in, reinstalled everything, and Merry Christmas to me - it started up and actually responded to the throttle. I'm not completely convinced it is fully operational but I'm reluctant to take the saw outside and piss rev it enough to be confident the problem is gone - don't want my neighbors to hate me.
Now for one more question. I've read of folks doing a gasket delete on these 55s with no mention of any mods to accommodate impulse. Is that possible? If so, what am I missing? The picture shows the impulse hole in the cylinder (out of focus in the foreground) and the deck in the back ground. If the cylinder base is flush to the deck, how does the pulse get to the carb?
Again, thanks to all who took the time to make suggestions. I may yet need them.
*** I'm almost afraid to check the compression now with the gasket in place. It was poor before, what'll it be now? OTOH, I'm told the owner is 82 years old and the easier it is to pull over, the happier his shoulders will be.