I will make a note of the heavier slide idea.
With regards your remarks on the dome motor nothing taken personally. This exercise is primarily to find out for my self how the dome motors made more HP but they have such a bad reputation that in talking to some of the guy's that rode them seems to always come down to a carburetion issue. I had a very brief talk with Mert Lawill but was not able to cover anything in depth. That will happen on another day. He ran dual mikuni carbs on his dirttracker in 69 and claims it worked well with a HP increase over the Tillotsons. If you look closley in On any Sunday you can see him on this bike at San Jose with two air cleaners splayed out and flopping around on what were hose mounts. It should be interesting to talk to him as he and Jim Belland were there at the end for the KR era. As an anicdote Mert said if HD would have let him run the KR in 70 instead of the iron XR he may have gotten the #1 plate again.
The plan, finances allowing, is to dyno this motor with dome and switch back to flat tops with a set of #7 heads and see what we find. I just cannot imagine that dual carbs by themselves won't be a big improvement . With the stock manifold your always jetting on the rich side because of the poor distribution of the stock "Y" on these motors.
Nice... I did have nearly the same set-up on the KHK some years back...
A good idea with square Spanish Amals on a H-D is to install the heavier brass slides... I know of and I have had quite a few stuck slides on the fully opened position... Kill button at the ready!!! I've also seen extentions fitted on the top to fit longer/stronger springs...
Now, Mike, don't take this personnaly/litteraly, I'm only after more info, but the H-D race shop couldn't make the domes work at the time, what are you doing today that you think will make them work?