Bob,
Your engine was built, around the same time as mine, by Steve Serano. When it was torn down I found out the heads were stock instead of 40 X 32 promised and the cam was nearly stock instead of the 110 as advertised. The case had never been cleaned and prepped and the decking was uneven. Those are just a few examples of what was revealed but the list was numerous.
Unlike you, I had nothing but problems with my engine up until the rebuild in 2010.
I suggest you call Ken Jansen 650-622-9785 or ask Bruce at Eyeball for a reccomendation to a local acvw engine builder. Chances are all you heads are new heads.
Remember, the carbs alone will do nothing to improve your performance, especially if you try to push that much more fuel and air through small intakes. If anything, it will reduce your low end torque.
BTW, I stuck with my 40 IDF Webers and increased the venturis for 28 to 34. Go to the Mechanic and Part Shop forum and get the link for Harney's Carburetor Clinc. You'll get the info on setting up your carbs properly for your specific application.