Boy, That pic of the Wellcraft brings back a lot of good memeories... I had one the same color w/ single 350/260 Merc. - Lots of partying going on with that baby!!
Wish I still had it - great picknick boat.
Not the fastest boat in the bay, but did get good mileage.
I looked at several SeaBirds- all very nice looking. But I can say they all had a delaminated/rotten core. One even had 3/8" ply (all cut up scraps)for coring.
There is a website for these things - someone had success adding lifting chines to the bottom...