Where to run the valve cover vent tube?

You can even buy a remote filter for it and not run it to the air inlet at all, but at WOT, if you do actually have blow-by, and the filter is too small, it will make a mess.
The common use of the term blow-by, does not necessarily have to be confined to applying to combustion gasses blowing past the rings.There can be other sources that masquerade as blow-by.
Such as; the crank picking up the oil and whipping it up, an overly rich mixture, overly exuberant oil-squirters, or just plain old inadequate baffling under the valve cover. Besides that are; vertical scratches in the cylinder walls, unusual oil drainage from the top end, possibly even late ignition timing.
If it was me, I'd be doing a LeakDown test, to see how bad it really is.