main seal direction

I recently purchased a 1968 triumph 500 daytona.I have stripped it down and while rebuilding have discovered the main seal goes in with the spring facing the clutch side unlike the commandos I have had which goes in with the spring side facing the crankcase. They both have timed cam breathers. I understand on the triumph it is to stop chaincase oil from being sucked in. The breather goes to the hose and to the rear fender.Funny back in 68 I had a new 500 tiger and had no leaks.I bought it new before my commando days.A friend of mine who also has a commando and a harley shovehead he has had for many years also says the seal goes like the triumph to stop the oil coming from the primary.He put the seal in like the commando a few years ago and now has oil from the primary coming in.We talked about this the other night and I mentioned I would post it and see what the forum thinks. I have the one way valve in my commando and no leaks.

Triumph spring out, BSA spring in, Norton spring in. All my BSA's and Norton's oils stay seperate.