You can use a 94-95 upper and have minimal trimming to do. I only had to work on the lip of the carb opening in the rear clip for mine to fit. Take a look at my
Build Thread -Sabre #??? for pics with the rear clip up. These flow a little better than the 88-93 upper as well and should be dirt cheap.
The tedius part is marrying the EFI harness to the chassis harness kits. And, of course doing it right: for EFI computer connections you should use soulder connection and not crimp ons. It's doable, and wierdo that I am, I kind of enjoyed it. One hint, the schematics that I used ('93 Mustang) had the A/C WOT cutout circuit wrong.
You can always change out the manifold an put a carb on as well. Then I'd just use a good aftermarket ignition.
Lynn