Here's wellcraft's numbers for a 1996 v21 with a 2.5L Mercury 200. You'd be lucky to get more out of the 3.0L . . . and with the open transom on the v20 . . . I personally wouldn't want the extra weight of a large displacement 225.
Spares the 2.4L 200 with fingerports is my favorite old two stroke motor. I think you'll see high 40's with that power.
