This is a very typical DB from the era. Retracts on .40 sized planes were relatively rare. I had Rhom Air on several of mine befor I got the MK mechanical. These were a bit lighter even though the required an additional servo.
I used a streamlined wheel all around. I don't remember the brand. They had harder rubber that stayed on during the high speed landings. I eventually add a spoiler/flap to each wing to slow down landings.
the nose gear opening was typically pretty ugly. I think it took away all the advantage of retracts. I made a gear door out of Fiberglas that I pulled a mold from a new model. It operated by the leg pulling a rubber band attached to the door. Very light and simple. I also had main doors but these broke off a couple times and were scrapped.
i had K&B 6.5 rear exhaust motors with the tuned pipe running through the canopy. These melted so I made molds again and had fiber glass canopys.
These planes were extremely fast. Right up there with the .60 size planes. I eventually ran the 7.5 ducted fan motors with tuned pipes and fuel pumps. These really picked up the pace of the planes. I won one of our club unlimited pylon events with one of them after my twin was disqualified.
These planes were relatively heavy. I think about 5 1/2 - 6 pounds so landed fast but really flew nice in the wind. I think the DB was the best of Bridi designs. I built and flew the .60 size ones as well as the UFO. The DB however was my favorite.
good od luck on your restoration.
byron