Most of the electronics on a 2-stroke 70 will be just fine after a dunking, if they're in good shape. Cracked coils, potting loose in a power pack, or frayed wires could be an issue, but if all was good when it went under, they should be okay.
Pull the carb cover off, the whole assembly. Pull the three hex bolts out of the bottoms of each carb bowl. With FRESH gas/oil mix, pump it through the fuel system to flush out any water. NO SMOKING!!! This is a messy operation, and laying some old towels in the belly pan might help keep it out of the water/driveway/yard. Once the carbs have been flushed, put the plugs bowl plugs back in. Allow everything to air out a bit and dispose of the rags/towels used to sop up the gas. Clean the spark plugs with carb cleaner, etc. Check for spark - a simple laying of the plugs against the block will suffice here. If you have spark, and you've spun the motor over to blow out water from inside, put the plugs back in and attempt to start the motor. You may have to remove and re-dry the plugs a time or two as water beads will foul them. Once you get it running, RUN IT! Heat is your friend. Idling at the dock won't do, get out and take a few laps around the bay. Let it run for 20-30 minutes to completely dry it out.
Once the motor has been run for a bit, you can now deal with the starter motor, as it likely has water in it. Remove the starter, and pop the bottom cap off. Take care not to lose any springs. Blow it out with compressed air, oil up the upper and lower bearings, and let it sit in the sun to dry out any residual moisture. A pair of putty knives can be used to hole the brushes in place when you reinstall the cap after drying. Would be a good time to inspect the brushes for wear while you're in there.
