here's my mount location picture.
here's the mount from the inside of the timing case.
With a timing chest mounted breather, most people drill at least one more hole into the crankcase to help move the air that is under pressure because of piston movement inside the crankcase. Needless to say the best place to vent crankcase pressure is directly from the crankcase. In the case of my 70 commando, I have a stock timed camshaft breather which works poorly at best in comparison to a reed valve bolted directly to the crankcase. Since I didn't have a breather port like the combat cases to bolt one of Jim comstock's breathers to, nor did I have the clearance to bolt Jim's sump plug breather, I modified my bike to breath through the plated off points location behind the timing side cover of my bike and hence it breaths through the timing chest well enough to have eliminated any oil leaks.
I warn you NOW, drilling holes into your crankcase is risky. It SHOULD be done while the bike is apart so the swarf and chips from drilling the holes can be kept out of the engine's insides... Did I do it that way? NO,... but I am a risk taker...
If you don't have a bike with an early frame, you can buy a sump breather from Jim and just bolt on a simple more effective solution than modifying your bike by disassembling, drilling, and sweating out any possible complications from your bastardization of your bike...