You think this setup will run okay? I've got the motor. I'm thinking of buying the boat from somebody.

Yes. It would be a lot better than tha 1648 in other thread. We used to run a 13hp longtail on a 1546allweld when tha river got 2 low for tha outboard and it did ok for wat we needed. U would prolly get around 20 mph with that setup with weight distributed rite.

"Blue collar" rig like mine- 27 HP LT on a 1648 grizzly. Stay away from big water, big chop, big current, know your carrying limitations, take all the requisite safety gear. Good, sound two man hunting blind. Get there early! Enjoy the ride! If you have ADD, are hyperactive and so on, forget about it!

I had a mb 25 on my 15 by 42 and i ran 18 with a decent load

It will run just fine. I've got a 35 (that's right, a 35) on a 1542 alumacraft and have hit 23.5 with two guys (both of us 220+ lbs). Heed the advise of a previous poster about staying away from big water / chop with what you're looking at putting together.

I run a 27 hp mb on my 1548 with no problems, you should expect upper teens with a light load. Those express boats are descent for a start up rig.