Hi Pim!

Verrrrrry interesting ! I had given up on the idea of even being able to fit my Empeg into my Alfa, but this sheds new light on the subject. Thanks a lot for that !

To answer your question : yes the GT dash is EXACTLY 100% the same as the dash of a 147. (except for the bit with the ashtray, but that's not important here)

I've also checked out that link you posted about the second DIN adapter. It looks A LOT like the one I've already bought. Crazymelki pointed me towards it then. (this is the adapter I bought.)
There's one problem with this adapter however : it's not 100% DIN complient. It's not even wide enough to slide the Empeg in, let alone make it fit perfectly because of the borders of the fascia. Maybe the adapter you're linking to is a different one, but it sure looks the same.

I also got your email, and will replie to it first chance I get.