More ideas for the 290TE/320TE/350TE:
Move the fuel forward and the kill boxes aft...that way the boat will not go bow down as the fuel is used up since it will sit on the CG.
Dicth the tuna door...I've pulled 200+ lb YFTs over the gunwale and would hate to try to leader a fish around to bring him between the motors...put one on the side a la Sea Vee instead.
Once the tuna door is eliminated, you can put a built in cooler/trash can between the livewells or even an optional extra fuel tank that holds 75-100 gallons.
Definitely have 300 gallons of fuel and twin 300 qt kill boxes. Make the coffin box optional or removeable.
Don't put built in steps in the forward storage...a single step (removeable?) would be much better if you intend to use the space as a cabin (which you need for a vacation home IRS tax break).
Put the batteries on the floor of the console instead of back under the livewells...that will make room for the most needed upgrade...
A pair of diesels with straight shafts for the 350TE/convertible or Merc Bravo3 drives for the 290/320TE.
'03 330TE, Zuke DF250s, Ray C-120 (2), RS-125 (2), 4KW dome, DSM300, M260, Icom 504A (2), CommandMic III (2), Navman Fuel 3100, Jensen MCD-A1, XM SkiFi II, DC Gold 6x9s (4), Odyssey PC2150 (2), BEP 717+, scuba rack, hardtop rear arch, extra rod holders