Worrying times, but if it's just the sills then you should be ok. I'm not sure where the mgzs/Rover 400/45 owners get them from, think I've geard them mention Rimmer Brothers? Could be wrong. Might be worth signing up to https://www.mg-rover.org/forums/mg-zs-rover-45-400.102/MG and pop a question up see if they know. Be prepared for the usual ridicule though (why not buy a Rover cos they're better etc) although some of the members are ok. I was banned from it many many moons ago because I run the site for the Civic version of the car! They took umbridge when I pointed out the that the "Rover Aerodecks" of which there were originally 2, but now theres 3 (3rd which appeared years after rover went out of production so obviously a member redressed civic aerodeck!) that there were never any rover decks. It's a long story but rover never put them into production but a lot of members there swear blind they did, hence I got banned! lol Might sign back up as I'm sure moods and opinions have mellowed now both cars are into modern classic territory.