Crankcase Evac Setup

I've always run my evac systems with closed valve covers,that is to say nothing but the evac breathers,no other breathers.
Am I correct in my thinking?

That is how we have always done it. I am wondering where in the collector to locate the hose nipple so that it won't hit the torsion bars, firewall, transmission etc.

I think Cope makes a valid point above. On an open headered drag car how much backpressure would feed back into the motor if the check valve failed?