Good morning, Robert! Your car looks great (love the alloys!) and the engine sounds like it's a blast. Re the idle jet plugging- make sure the air filter tops and bottoms are sealing well. The chromed sheet metal pieces are known to leak and a little bit of grease (not sure what type you'd use- maybe someone can chime in here) on the bottom and top edges of the filter itself will help seal them up. If the filters have 1 screw holding the top down, I've heard of people distorting the hold down bracket a little to get the top to sit tighter. If you have cast aluminum pieces, make sure they are flat, the filter flanges sit within them properly and the bottoms sit on the carb tops properly. I guess I missed it- what carbs does the engine have?
Do you know what the heads flow? It would be interesting, given the narrower lobe centers on the cam, to see what would happen with 1.4 rockers. I'm guessing that since it is a 2276, adding more lift (and a wee bit more duration), while being more powerful, won't really detract from the bottom end/lower midrange that it already has.
And thank you for the concern re the my cousin's journey with pancreatic cancer, but (as you know, because you've faced it) watching from the sideline is nothing compared to what Robin had to endure. Al