We have a 1997 302 Boss w/ 7.4 Mercs. We love the boat, especially the color scheme and ammenities. Top speed is right at 60MPH. I'd like some suggestions about upgrading my current 7.4's or replacing the motors all together. I've read that the 7.4's are not a good platform to build on. I appreciate your input.

to get a noticable increase in speed you will either need to repower with 415hp 502's are install a pair of low pressure superchargers, and have the ecm's remapped on your 7.4's, anything less will most likely not give the speed you are looking for.
Mark

You heard correct
the 7.4's do not have forged parts, they are mainly cast.
You really need to start with a 4 bolt main block.Steel crank.
forged pistons and rods.
these come stock on all of the magnum motors.

Good luck

repower then sell stock motors