DDD - the book you get tomorrow , I believe has the cam specs in it for the stock cam.

I have all cams specs, but unfortunately on my portable hard drive which is at home.

The l29 and everything that goes with it was made for emmissions spec truck duty , and heavy boats .when it came out they had the carb the tbi the mag the ski the walthers v drive edition I think even mercruiser was a little confused
The gen 6 mpi isn't a bad motor ,the zz4 cam went to the edelbrock ovals you may run into some pushrod issue madness if you get the valvetrain geometry right and spring pressure science sorted , then you have to deal with potential reversion with cast exhaust using a 502 cam in 454 ..verify those are NEW heads not city motor New. heads ...2nd string vortec replacement valves lose their heads almost instantly when water hits them .see what if the hp500 wants for spring pressure then see what you have there ,ill bet that will at least tell you
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If you springs are even close .I would recommend a Jr zz502 iron oval 781's 049 cheap ,intakes o plenty you won't have to break new ground . Just have to get the right head gaskets .or find a boat with a cracked gen6 mpi swap sell hop up ect .still going to need longer exhaust primary pipe length to exploit the potential of a rumpety rump cam .and help with reversion