My advice is whatever you think will work get one 2 feet longer, 1 foot wider and 10 more hp.
I would love to see a picture of your set up if you have one and are willing to share?I had a 1654 lowe roughneck with a 50 merc, i actually just sold it.
Great size boat fun to drive easy to load and would hold it own in rougher water. I ended up doing a little work to the motor and i could run 40 in it. I have had 4 people in it and it still would run 34ish.