It makes sense to me to use a single donor, as 9 times out of 10 you'll have all the parts you need in the donor, I cant see the point in buying an MX5 then throwing away uprights designed for wishbone suspension to replace it with parts that have been adapted to wishbone suspension. The MX5 is good for this that's why so many are going down that route.
There's other annoying things too like different PCD for the wheels, etc etc.
Matt, I've looked at the pictures, I'll sit down over the next week and put something to paper (well CAD)
I've got to do a couple of things for Chris's single seater first.
Kind regards
John