Well, the valve covers look to be between 65-68 ? Something like that.
So being correct for your 75 isn't going to happen.
Having said that, since you painted them up so nice, why not use them. But first lets get a couple things straight. What you have now is 2 breathers. These are generally called "push on" breathers. What you want to do, is have 1 breather and 1 pcv valve. The breather will be on the driver side, the pcv will be on the passenger side. Here is a pic as an example.
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