If ya wanted a good set of heads, you should have kept the Chebby 
2sav 
Oh right, 2sav, with the factory iron chebby's inferior intake port, inferior spark plug location, inferior valve angles, inferior combustion chamber shape, inferior coumbustion chamber volumes, ETCETERA (sheez do I have to go on?).
Uh-oh, here comes that damn FoMoCo vs Gm thing again.

Hey 429heads, E7's or F3's?

How about I pattern my plate (onto cardboard) for you to duplicate?


Actually, probably the easiest thing for you to do is to pattern a Glenwood (etc) jet boat plate onto some 3/8" 6061 with room to extend the bottom of the plate edge to v-drive spec....and then just machine your typical jet boat waterpump block-off plate for the v-drive waterpump.
LO