They do fit I think - I am pretty sure there is a SPF with a mod motor Ford in it on this forum or passing through my email some time ago. Not sure on the transaxle though.
A Texas speed shop (Dallas Performance) built a MKIII with a nasty sounding 1,200 h.p., TT SBF hooked to a Ricardo few years back. 'Needed mods to mount the Ricardo as I recall.
Owner of the car totaled it on his first(?) outing...'had something to do with the extra rear weight bias of the Ricardo + speed causing a handling problem. 'Car launched off the road backwards and that was that.
It sure was impressive looking / sounding.
'Stunning in fact.