On an engine of 1966 vintage you have 2 issues to worry about. Wear in the carbon thirst release bearing is one. The other is wear in the crankshaft thrust washers. I bought a Triumph Spitfire in the 70's which turned out to have >5mm end float on the crank shaft. The block was only fit for scrap. Not sure if the TR engines suffer the same weakness of thrust bearings as the 1296 Spitfire / Herald unit.
