Not in the dash, and it's a Garmin 545 instead of a 740, but it fits quite nicely in the corner of the windshield on my '01 22 with a small bracket to mount it.
I don't think there would be any trouble putting the 740 in the dash if you re-arranged the gauges. The only thing I would worry about is the viewing angle and keeping it close to the driver so you can see and reach it easily. I do think you're on the right track wanting the bigger screen - I always recomend to my clients to go with the biggest screen they can as when you're actually out on the boat bigger is better.
Don
'01 22 Classic, 502/B1
And a bunch of other stuff
"If everything seems under control, you're just not going fast enough" - Mario Andretti