your current heads are going to be down on power compared to the more modern ricardo combustion chamber found in vortec's etc. however you have them. The torquers are heavier (thicker) than the vortecs, and while they have larger valves, they flow more than the old chev castings, just not as much as the vortec.
did you at least do a proper piston, or did you stick with the cast flat-tops with the 4-piston reliefs?
with any cam change on a boat motor, you need to stay below 270 degrees of duration or you end up sucking water into the motor thru the exhaust.
I would highly recommend a roller motor myself. however for your old flat tappet motor.... I ran a comp cam - the CL12-236-3 - Comp Cams 'Xtreme Marine' Hydraulic Flat Tappet on the 350 in the Rogue prior to going porkchop
Operating Range: 1300-5500 RPM
Duration Advertised: 262 Intake / 268 Exhaust
Duration @ .050'' Lift: 218 Intake / 224 Exhaust
Valve Lift w/1.5 Rockers: .462'' Intake / .477'' Exhaust
Lobe Separation Angle: 112
ran it with summit 1.52:1 roller rockers when I did a vortec head swap and a Volvo Penta marine intake (same as edelbrock marine intake). I should have gone with 1.6's as I had room on the PTV test.
with any flat-tappet cam. the first 20 minutes of break-in are critical.