OUTLAW EAGLE MANUFACTURING

[Wrench900]

New to the forum. Love all the info specifically related to jet boats!
Got a 21 ft North River two years ago. Great boat and love going up and down the river. Way more enjoyable than doing circles around a lake.
So here's my question. It's a 1990(?) and has a 351w coupled to a Kodiak 3 stage. This winter I've decided its time pull the motor and either freshen it up or what I'm leaning to is putting in a GM 6L. Just looking for any in site people could pass on. I would say I'm more than capable of doing the majority of the wrenching related to the project but would like some experienced input.
Do I keep the 351? If I do I think this would be the time to bore it out and add a few more ponies, say 393 or 408. I believe this would be a good setup and since the rpm is in the mid range it would last a while.
What I'd really like to do is the 6L but this is where I need my path steered a bit for me. I've looked at new engines, getting one from a wrecker and converting it over and used as well (when I can find one). I'm just on the fence with options.
I would love to goto some of the events around here and try new areas but just don't think the old girl has the jam to pull it off as is and I don't want to be the guy that has to be towed back to the trailer ruining someone else's day.
Like I said.. Just looking for some input.
Thanks