You got a WELL FUNCTIONINGPCV valve on one side and an UNBLOCKED breather on the other it'll be fine. A little puffing is normal at the beginning. Provided its just puff and not pure liquid. I mean does your valve covers baffle really well?I'm sure if you hold your palm over the hole you'll find it looks like more pressure than it is. So
1)if its a newish engine it will blow by more than when it gets broke in
2)just make sure you give it that loop to follow. Good breather on one side,good pcv on the other.

PS. I never seen an engine that didnt blow like a steam engine first while. They need break in time and the above