He has a set of banana grooves so that's probably worth a try.

Definately not blocked, shaft or rocker itself.

The thread difference is very minor between this rocker and the others.

Does anyone have a comment about the oil? - from their website "Penrite HPR 30 is a premium mineral SAE 20W-60 non-friction modified petrol engine oil". He's concerned about excessive oil pressure. and has read somewhere that Mopar small blocks should only run about 40psi at idle. I can understand that for a stock (ish) engine but this one idles quite fast and I would have though 70 psi is up there but still ok.

I'll pop over there at some stage and try and get some photo's