You'll need at least a 3/8" diameter hose flowing its full capacity to support a PCV valve properly. Drilling/tapping for a 3/8" NPT elbow or nipple is a very good idea. Look at the fittings a later-model engine uses for PCV plumbing to get an idea what it's going to take to flow enough air, and plumb your engine accordingly. The smallest, most restrictive fitting in the line will establish the maximum flow, so don't put any choke points in there.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!