Interference fit amount for connecting rod bearing races 1921 F 61", + Pistons?

[Mike21F]

Hi from Aus. I'm just about to start my engine rebiuld and I can't find the amount of interference fit required for pressing in the con rod bearing race rings. Would 0.0025" be about right? Or would 0.004" be more correct as someone advised me? This sounds a bit tight to me. Any suggestions? Also, has anyone used the forged 61" pistons from Competition Distributing? I have been trying to contact them by email, but have not had any replies yet. I see that they are not shipping anything until October. Are they closed temporarily?
I would love to hear what you might suggest. Thanks in advance.

Mike21F.