We installed my R380 with a floor jack, so changing the mounts is doable. I'm not sure though that there is enough clearance between the top of the gearbox and the seatbox/tranny tunnel to lift the studs on the mounts clear. Worst case, you have to unbolt the chassis mounts. Three long bolts on each side if I remember correctly.
Ex-Mod 110 Tdi
Series 3 88 Diesel Soft Top