Tricketts did mine, with the engine in situ but obvisouly supported, the cut out all the bad stuff near the front righ hand wheel, treated the remaining metal inside, added fillets and bracing, repainted then sealed it all up and the painted the outside. They do a proper job, it's worth a trip down there and they have some exotic F275 and some non-exotic basket cases (R4!) which need the the whole floor replacing.