I have done a Windsor to Romeo swap. So I am speaking from personal real world experience. I have put over 100K miles on my Mustang after the swap. So by most any measure the swap was a success.
When I did my swap I decided not to re-use the original 10.5" clutch. Instead upgrade to a later model year 11" clutch. Basically using the 2001 model year as an example of parts to match towards.
My donor motor came from a 2003 Grand Marquis. So I sourced a 6 bolt 11" clutch flywheel from a 2001+ Mustang. And yes I did have to add a pilot bearing to the donor motor.
In your case should you wish to stick with the current 10.5" clutch, then look for a 6 bolt Romeo flywheel from a 1996-1998 Mustang GT.
Try searching on car-part.com for some example salvage yards with the parts.
Or buy a new flywheel online.
As far as the flywheel to motor is concerned, the only thing to look at is the number of bolt holes is the same as the motor.
When ordering a clutch, make sure it's the same size as the dowel pins on the flywheel and that the pressure plate has the same number of splines as the transmission.
This topic has been covered a bunch of times in the forums. Search for "Windsor to Romeo swap". Good luck!
