Thank you for the feedback. In the TE/AE Field Guide To Sunbeam
Alpines it says that Series IV bodies were used to make Tiger Mark 1 cars. If this is so then I imagine that doors off a Tiger Mark 1 would work as well as Series IV. They also say that Series V bodies were used for Tiger Mark 1a and Mark 2 cars, so those would have the square corners. I am also assuming that door from Series I, II and III Alpines would not fit.