There's a 22op guide boat in ukee with a 200 Yam. He does fine and fishes 5 guys on occasion. Don't go any lighter than that. That is a 2006 hull and I know the design has seen some updates so I'd suspect it has become slightly more robust.
If its an older hull and you go with the 200 which I'd say is the minimum ponies I'd go merc over yam or zuk as the merc is a 3.4l vs 2.7 (approx). Displacement matters and the smaller blocks are juiced 150s.
I'd go with a 250 of your choice if it's a new hull. Whichever brand you have good local support for would be my preference. Yam, merc, zuk all make good 250s.