BSA 770 cc V Twin, 1930 Black Mountain adventure 4 - Trouble ahead?

The engine re started easily at the far side of the Mountain and we set off for the more gradual climb to the top from the Brynamman side, only to start getting hot and bothered and losing power near the end of the haul. We just had to make it the last half mile or so to refuge in the top carpark, but would we get there, with me nursing the engine, or would it seize with us so close?