the MIC DBB is DICKERSON BOAT BLDRS TRAPPE LANDING PO BOX 92 TRAPPE MD
You have a Seidelmann 30 built by Dickerson. Dickerson may still have drawings, or even molds for the board, if not I can help you with the board shape. The way this board is installed is unique, the top of the trailing edge rides on a traveler mounted inside the trunk. The leading edge rides on a trailer roller. There are lead castings on both sides of the centerboard trunk under the cabin sole for ballast the board is only lightly ballasted to overcome its buoyancy.
To convert to a fixed keel Take up cabin sole, chainsaw the lead in to pieces you can handle, cutout centerboard trunk, Purchase a lead keel Seidelmann 299 would work well, make an insert to fit the keel, relaminate the bottom and reinforce the laminate to take the additional load of the fin keel, fabricate floor frames, laminate in place, install a new cabin sole and bolt on your new keel. I did this to a Seidelmann 25 but I was much younger then....and I had the factory to play in.