I will definitely let you all know how and if things improve. I'm taking a little forced hiatus from even working on it in the garage because temps here have been around 115 Fahrenheit. I'm pretty good up to 105 and I will do 110, but that's where I draw the line!
I would have to think that if the engine is behaving as B.W. describes some of them do that retarding the intake timing would indeed smooth things up a bit. If the valve is closing before the crank is bringing the piston back up, it seems like there would be an ever so slight vacuum to overcome. That probably wouldn't make a huge difference for the most part, but I could easily see how it might limit revs and cause some resonance. Anyway, as has been said earlier, it won't hurt to try - at worst I might lose a PSI or two of compression if the valve closes a bit late.
Thanks for the input on the tires, Mick (tyres is the better spelling to separate noun from verb - but alas, I am on the other side of the pond). Though the tread on my Avons is still very good, the cracks in the sidewall indicate they may be a bit long in the tooth, so I might be able widen that diameter a little sooner than later. A very good suggestion - while I do love the look of that Speedmaster, I don't have particular notions about the Safety Mileage.