Mattie,
Is this 3.8L going into a MII?
What tranny are you planning to use?
I think that you will come a lot closer getting 5.0L components to fit than 2.8L parts. The 3.8L V6 is like 3/4 of a 5.0L V8 where as the 2.8L belongs to a completely different family.
Can you get a pic of the back of the motor so that we can compare the bellhousing mount to a 302?
What kind of oilpan doesn it have, front or rear sump?
What kind of fuel system are you considering carb or EFI?
I think that the 3.8L V6 would be a great match for the MII. I was thinking along the lines of the '99+ version with 190hp stock, EFI, and a 5-speed from a late Mustang.
There's probably not much experience with 3.8L V6 models prior to '94 on the V6 forum. I think that they only came in the Fox Mustang in say '83-'86 and then only with AT and throttle-body injection.
78CobraII