Venting Early Commando Engines

Any suggestions on how to reduce the crankcase pressure in the early Commando engines (1968 - 1971)? I noticed some suggestions on this forum and on the INOA site for using a power brake check valve #80190 on the 1972 and up Commandos. Is there any reason why the check valve can't be used on the earlier Commandos? Will it not fit? Can something else be used?

Thanks,

Stephen Hill
1968 Fastback
1970 Mercury
1971 Roadster
1974 Interstate

The earlier engines with the breather hose coming out of the left side of the cam-tunnel already have a rudimentary system with a slotted disc driven by the cam that acts as a one way valve. I wouldn't have thought there would be any additional benefit derived from putting a one way vacuum valve on this hose, but you might consider adding one or more additional breathers to the engine and having a vaccuum valve on this/these. There have been numerous posts on this site about this if you trawl back through previous posts using the search function.