If you have just taken this bit of ground on you might be able to ask around as to how the previous tenant dealt with it, have a word with a neighbour see if they know, it might help you make up your mind. I spent a lot of time in the seat of a 135 back in the day, no cab then just a roll bar when they came, seems crazy now. Anyway, even with the best cab on - rusted or not, rolling down a hill is going to seriously mess your day up so I wouldn't chance it myself, think of your family.