Had a go at overlaying a mustang fastback myself, added some wide arches and a splitter. Means it becomes a hatchback but has better access to the rear. Inspiration was the 1970 aston dbs and 1967 ford mustang of the bullet period.
Here's a clue . The above pic is a smoothed version of how its going to look. At the moment the roof is in half and the lights aren't in yet. No glass is in yet. Still waiting on honeybourne mouldings to deliver the product I paid for some weeks ago. Which is delaying the finish of the roof and rear wing finishes
Still trying to workout how to put a stainless steel panel down the sill but it'll get their some day. Bit like 1967 mustang and iOS grifo finishes. Chrome or gun metal side window surround. Need to source a gutter to run down it as as well to keep it period. Details and spec that kind of thing . Bonnet scoop height is going to raise a little to mimic the wing shape
Some have compared the look of the pic above as a fiat 1500s. Some n aston martin of the 70's so not bad . Shape on the back is coming along nicely. Learning as i go. Trying to also incorporate a hatch into the back part fibreglass part metal. Domething similar shape to the jag xf have also been looking at the audi r8bhatch to see how to incorporate the mx5s width and keep the concave shape along the wing. Aiming now for an october finish seems more reasonable as i only get about 32 hours a month to work on it.