If you are fatso.... then I am a super tanker

At 103 Kg I find 140 liters to be very ample float wise.... stability comes from many aspect of shape.
One thing that I have found, Shape matters.... numbers mean nothing from a surfability standpoint. I have tried many boards that looked good, had great numbers, but are dogs in the surf.
It sounds like you are really well suited for my favorite board, the Fanatic Prowave 9'6 x 31.25 @ 150 liters. Very lively in all size surf.
It is a very comfortable "Big Boy Performance Board" I bought it for big winter surf in snow country.... but was really surprised how well it surfs small stuff as well. Great paddler, super stable in crap conditions.... check out my full review in Board Talk (9'6 Prowave review)
Pretty easy on the wallet in the HRS version.
I currently own 4 different boards... Hobie 8'11 RAW, Fanatic 9'6 Prowave, Naish 10'6 Alana & Laird 10'6 Surfer