My 496's are running at almost 190. I know this isn't normal and I'm running out of ideas of what to check. Sea water pumps are brand new,oil coolers are clear and heat exchangers are clear. Where do I go next?

How many seasons on the antifreeze?
How is your water pressure?

You might check the water pickup in the drive. I had a 496 VP that would run hot, turned out to be a kinked water line in the drive. Just a thought!

Haven't checked the water pressure and coolant is brand new

You need to use a scan tool to verify the engine temp, read the seawater pump pressure and the port and starboard manifold temps. Go from there. The pump pressure should be around 2.2 PSI at idle and a minimum of 20 at 4000 rpm. Maybe a new thermostat as well.

I was thinking that you should check the thermostat also.