Reassembly -Head back from the machine shop, actually had 8 thou removed, so the heat had certainly done some damage. Christian from RPS came down to my workshop to refit the head and modified/repaired radiator. All went well until he tried to fire up the engine, the engine would not fire. A quick look and he found an issue with the distributor the shaft would not rotate freely and had partially seized, unfamiliar with my workshop and unable to get hold of me, he could not find a blow torch to try and ease off the shaft so he left with the distributor. The new modified inlet to the top tank of the rad looks good and will hopefully be the end of leaking radiator !