Here is a link to the Comp Cams solid "dumbbell" lifter:
https://www.summitracing.com/int/par...5-16/overview/
Based on the advice being given, I should be buying new lifters in any case. In retrospect, it would probably have been easier to buy a new cam and lifters from the outset, rather than buying dcdoug's used items.
I've had a closer look at the other lifters that I took out of the engine and they're worn flat on the cam end, rather than having the necessary convex profile, so they were all on the way out.
Paul