Makes me think the 1/4" inch would be fine for my build. Merc used the same mount on just about everything up the 600SC..

Hardin makes a filter head that uses 1/2" NPT. And accepts WIX #692-33405 filters.
Black Anodized, High Volume HP4 Oil Filter Head and Bracket 1/2" NPT Inlet and Outlet - Hardin Marine
I believe CP stocks these as well.

I've looked at that many times.. Just don't think it's necessary for this build. Just a mild NA 454.
Think I'll just run the stock for now. Spring is here..

you Can drill out the stock head and retap it. I've done it. works