Ron,
BL Special Tuning used to sell a kit for the 1275GT which included a well modified head with about 16cc chamber, a pair of Twin HS4 carbs, and I think this may have also used the offset rocker bushes and modified distributor. My suggestion would be to try and recreate this engine spec. Basically the modified head, higher lift rockers, and big carbs will reduce the volumetric efficiency at lower rpm, making it less liable to pink under load, while the short timing of the standard cam will reduce the volumetric efficiency at high rpm.
So just add on twin HS4s and 1.5 ratio rockers!
You will also likely need to use diet of best available petrol (Shell or Tesco 99) with either Valvemaster + or TetraBoost.
