Thanks for the response I felt that the 4cyl's would have worked fine for me but in keeping the 150's I will be able to still fish and spend the cash on some cosmetics namely the soft hatches. I also will be rebuilding the transom soon and closing it up and building a custom bracket the money I saved buy not buying the 4cyls will pay for all the transom materials and the aluminum for the bracket.
I get to see and work with lots of different power/boat configurations at the salvage yard and even though never any sc's w/4cyl's but our 26 boston whaler guardian came with looper 140's and would run 38mph loaded and by the way the guardian's hull is 4inches thick, although i don't have its weight its a very heavy load behind the f350 truck we pull it with. Also ive seen several grady's with the x-flow 4 cyl's on 20 to 25 ft boats that all seemed to preform acceptably.