Michael........I would drill another hole in that breather box and connect both hoses from 1-2 & 3-4. I like that you put it in that "void area", out of site. I too, had trouble with those "C" channel CB covers plus the bolts that hold them on leaked too so I went back to stock steel/snap bail covers and never had another leak. Also I welded steel tube connections into these covers (again, no leaks now) to connect the hoses to. I have found that using the valve cover gaskets that are made of black rubber impregnated cork work the best. lastly, I spot welded a small flat piece of 22ga sheet metal tothe the bottom/inner cover wall to keep the gasket from drifting up and out of it's sealing area. Similar to what's on the top.
I have to mention too, that I used "Total Seal" piston rings during assembly. Measured with my trusty Manometer, I had no crankcase pressure what-so-ever ! When you order a set of Total-Seal rings for the 90mm pistons, only the second oil ring is used and it has the trade-mark piston ring end gap seal. When testing piston ring seal using standard leak-down procedure I was surprised how high it was compared to stock ring set readings.
The only reason I mention this is if any of you are building and engine right now, I recommend installing a set of Tota-Seal rings. You won't have any blow-by to worry about, plus the compression stays up there where its supposed to and no increased friction from these rings as well.................Bruce