Thanks TG, they're 57mm bore, 0.8, 0.8, 1.9mm. However I'm just off the phone with the Wiseco guy I've dealt with previously. They are presently making special order pistons for a customer who sourced rings from this TKRJ company. The customer was happy with what he received. He claims they are either an OEM ring producer or reproducing OEM spec rings and I should have faith!
I've been pleased with this guy in the past so his reassurance is enough for me. We'll give them a go.