[tsubaki]

Welcome to the site!!
You'd be surprised how little the soaked foam will add weight to the boat.
We did a reno on an Ashcraft ripoff, convinced the boat was full of water in the foam. After 2 months poking holes, elevating and trying draining the boat we got only 5-8 gallons out of the inner bottom.
Primary consern would be the condition of the tank with the constant (salt) moisture, if it ain't smellin like gas it probably will be allright.
44mph with a 150 is goood, don't sound like no weight issues there!
Being you got foam, the stringer problem may not be an issue till you really need to get inbetween the two shells. BTW other than the wood in the bilge why do you feel the stringers are (should be) rotten? Normally they are surrounded with cloth and resin.
YES, pictures are expected!!