I've been wanting to do this for some time now. I think the Buck Rogers Thunderfighter is one of the best looking sci-fi ships out there - easily top 3 for me (along with the X-wing and the Colonial Viper). The 1:18 Mego version is really quite good, if not for all its fragile parts and lack of sculpted details (the toy's stickers were also pretty weird). So I rescued a severely yellowed one, stripped the stickers and painted it up mostly following the old Monogram model kit layout.
I further added a seat and stick from a busted old FANG. All the typically rare parts (nosecones, fins, cockpit hatch, landing gear) are repro, and I used a couple of vintage but split engine nacelles, so no valuable components were harmed. I still have 3 other starfighters including one near pristine one. But I love how this turned out. The only real nuisance were the repro fins that were some seriously unpaintable plastic. Took multiple attempts with sanding and repainting. They're a little ugly (you can especially see it from the bottom shot), but work well enough for me.