your propably on to somthing... the IRS is just me trying to overcomplicate matters anyway, i had a jag IRS on the deuce. and it was so freakin heavy you wouldnt believe...
i will look into some different options rear suspension wise, but leafs are out
perhaps a 3 link?
not sure how much cornering potential teh mustang 2 IFS has, and what one can do to optimise geometry...