Trying to cobble together a bbc cast valve cover analogy that parallels buying a pair of shoes getting home and they are both lefts . All you can do now is get blowby (hopefully minimal) out through 502 mag specific fitting and back over somewhere where it re enteres the engine goes out the exhaust and you never smell or see it.
thats all that really counts unless they do a visual smog check where your at.
have to watch those bbc alum valve covers if your going custom . They all kind of look the same at first glance but ...

I got a Bridgeport and a Monarch, nothing is proprietary.

It was roughed in on the dyno and made 497. We'll fine tune it in the boat.

On most models merc tied port and starboard together then it ran to the bottom of the flame arrestor..it would rely on the suction of the throttle body to suck the crankcase clean..

problem with PCV is at high throttle there is no engine vacuum. and more blowby. that is why it is put into flame arrestor. PCV is fine for sportfish that spend their lives at part throttle. but a high perf engine needs blowby routed straight to intake air. although you seem to only smell blowby at no-wake speeds. that is when having PCV also is nice...

If it goes to the flame arrestor it's not a pcv its just a plastic hollow pcv looking thing with no spring and guts inside that fits the valve covers hole. If it goes to the back of the carb or intake then it uses a real pcv valve.

As long as it vent to the intake and not my bilge compartment, I'll be a happy camper.

Best way to go is PCV to manifold vacuum on 1 side and straight vent hose to flame arrestor on other side.

Between the links below would be all the OEM parts that completed the stock set up.
http://www.mercruiserparts.com/Show_...d+Rocker+Cover
http://www.mercruiserparts.com/Show_...+Intake+Plenum

^^^, The parts above would of had the hose connect to the flame arrestor which started in 1997. 1996 Merc used item number 31 which would allow the vent hose rest just on the under side of the flame arrester.

http://www.mercruiserparts.com/Show_...D+ROCKER+COVER
http://www.mercruiserparts.com/Show_...+INTAKE+PLENUM

^^^, Same with 1993-95 as 96 but different hose routing,
http://www.mercruiserparts.com/Show_...D+ROCKER+COVER
http://www.mercruiserparts.com/Show_...+INTAKE+PLENUM

Here's the pic:

is that an actual merc diagram? big block valve covers on small block heads?