Thanks everyone for the input.
Nice to see the actual bolts - thanks Bergs. Must say 3/8" dia is more like it than an undercut 5/16" - maybe the ones the guy on the internet was referring to were RR or someone else's? I'd have expected the bolts to be UNC (or metric coarse) as they appear to be screwed directly into the alloy with no steel insert in the rod - but then again the coarser the thread the weaker the bolt due to reduced core diameter.
Swarfy - yep, the GF was another case of grief. Reckon my son's about right concerning my karma. However, the elusive lubrication problem was solved by a suggestion from a forum member (forget whom now). Despite oil pump and crankcase and gasket holes all lining up, a gasket with bigger oil holes was the secret. Doesn't make sense, but it worked. That bike has been on the road a while now, but old, mis-matched conrods worry me. I don't ride like an idiot, but I do like to blast through the gears to enjoy an engine. At present I'm loathe to do that. Also, there's more vibration from mid revs up than I like, so new rods and a re-balance over the winter is the plan, now that the vee twin is finally finished. Trying to resolve seemingly insurmountable problems with the latter's starter motor was not only perplexing but took up around 6 mths of my time.