I have used an MSD 6010 for a number of years in saltwater no issue on 2 different motors 5.3 and 6.0. It was mounted under my rear seat not on the intake. Company in daytona make a system similar to the msd. Also used to be when they had 6010 box there were 2 different versions. One the came as a kit with edlebrock intake. Harness was shorter and you could only use the pills to set the timing. The one not in the kit harness was slightly longer and you could program your own timing curve.
I believe that the current model has a dashpot switch that allows you to use it on a 24x or 58x motor and several other options.
I did take a harness and strip it down (LT1swap.com has specific info on which wires to remove) and had it ready to use. Still need to reprogram computer either have it done or buy HP tuners.
never used it because A buddy has Holley HP and didn't care for it (left him stranded, his fault though) and want to change to a carb. I got a Holley Hp System cheap. Easy to install and set up. Had it for 2 years now and like it so far.