OK, diving more into it.
The main difference between the two bellhousing is in fact starter clocking due to the difference in flywheel diameters. If you bolted in the 10.5" flywheel the starter won't contact the flywheel. The 3.8L flywheel is larger in diameter, so you could possibly use the truck flywheel and clutch but I've never actually seen or heard of someone doing this. Just much easier to use a 94-95 bellhousing and use standard Mustang parts (10.5" flywheel and clutch). If oyu want to try it, you need a 164 tooth, 50 oz flywheel. I personally haven't searched so I don't know what exists for these. I would assume you want a clutch kit for the flywheel you get, but unsure if th clutch disk spline count will match the t5 spline count as the f150 didn't used the t5 and had a few trans used.
One issue with the SN95 trans is the bellhousing is deeper pushing the trans back about 3/4" Might require some trimming to the trans tunnel to get it to fit.
I would recommend however that you try and keep the car as close to standard fox components as you can. You can convert that t-5 to fox input shaft length if you wanted. Just a recommendation of course.