Speak to Style to Design. IMO they make are the best re-trimmed original Mini seats available and they will fit straight in. They have tooled up to have their own design of seat foams moulded, the only thing I would change about mine is the thickness of the rear bench cushion, it's very high. The only seats that will fit straight in without work are those designed to fit, so original seats or aftermarket seats with Mini subframes. Seats from any other car that you just find, including an MGB, will need some sort of work to fit them. Where they are normal aftermarket seats made to fit another model, such as the many Recaros found in high spec models, new frames may be available that will allow the swap. But in the case of anything like the MGB seats you linked above there will be work needed because they aren't designed to fit or to be interchangeable.