Excepting the obvious Fiero rebody kits, one that's not too bad is at
http://www.factoryfive.com/table/ffr...tmrelease.html
Corvette suspension/engine and Porsche transaxle. Not yet for sale, but promised soon.
Also interesting, but I think not street legal is one at
http://www.millerteamracing.com/
While not mid-engined, I've been trying pretty unsuccesfully to talk my wife into a Cobra Daytona Coupe kit. Still I buy the magazines from time to time.