We just purchased a 32ft searay with twin 91 Chevy 350's the manual says 750 idle but with the screw backed off all the way on the carb its at 900 and smells rich I havent been able to take a look yet but thats what my dad said. It also said 8* timing stock. Sound good? what else to look for? Thanks

 

Disconnect the throttle cable and see if RPMs will lower by turning idle speed screw. Cable may be keeping butterflys from closing all the way and needs adjustment.
Butterflys may need to be loosened and re-centered in their bores, but this is unlikely unless carb was just re-built.

Does it have a choke? Is it opening all the way?
Most boats have electric chokes and take a few mins to heat-up.
Find idle mixture screws. (They may have a funny figure 8 shaped head) Turn them all the way in, but stop when you first feel resistance, any tighter and they will be damaged. (Be sure to count exactly how many turns it takes, so you can un-do your adj if needed)
Open them 1 1/2 turns. Start eng. and run till choke is open. Adj idle RPM if needed.
Close one screw and see if eng dies or nearly dies.
Open both screws to 1 1/2 turns again and close the other screw.
If eng does not respond to closing one of the mixture screws, you need a dip and a rebuilt kit. Not un-common to need a rebuild every year with the boats usually sitting around all winter.
If mixture screws are working. Adjust them equally out till max rpm is found. Turn them back in slowly till rpms make a noticeable drop, then back them out 1/4 turn.

Also check float bowl fuel level and fuel press.
Keep in mind float bowl level changes when boat is in the water due to everything being at a different angle.

Don't know what timing would be for that year eng.
My 84 Mercrusier 260 (Chevy 350 w/ 260 HP) calls for 8*BTDC.

Be sure rich smell isn't a fuel leak.
Since you own a 32' boat, I'm assuming you've owned a few boats previously and I will skip the "how dangerous fuel leaks on boats are" speech.