For a single 4 barrel hi performaance carb on a hi perf 350 the 750cfm holley is the best choice
99% of the time. It is every bit as responsive as a 650 if not more and aways makes more power
If you want to actually make your boat go faster get a tunnel ram and two 650's or it.
The edelbrock street tunnel ram is a good choice. Now you will gain some MPH on the water.
This chart illustrates the power gain from a single 4bbl to a tunnel ram w 2 650's.
This 355sbc is similar to yours
while the power test starts at 4500rpm the tunnel ram will out power any single 4 bbl manifold typically from as low as 2500-2800 rpm. You will have more mid range power.