Soon there will be, here is a little vid I seen recently:Is there any mod, or adapter, so that I can use a G27 Shifter on a T300 or T500 wheel?
You can keep abreast of it here: http://www.basherboards.com/forum/thread-333.html
I can vouch for the great product by mrbasher. Works flawlessly with my setup. Great if you don't want to milk out lots of moolah for the TH8A or TH8RS. Orrrr would rather have the convenience to switch both sequential and H-shifter for you lazy guys like me.
All mrbasher's products have a good reputation. This is why I really hope he introduce this adapter on the working agenda.
As I understand, you have already tested and you're satisfied. How did you to find it?