I looked at the Tadpole conversion so be interested to hear how it sounds. Where are you going to put the Sony unit?
It sounds fab
The way it works is that the vintage RadioMobile head unit is modified to become nothing more than a set of passive switches to control the Sony head unit - which does all the work. If you've ever used a Sony rotary commander then it works in precisely the same way. So the sound is down to the Sony unit. I went for a DAB unit (CDX 6650) though may see if I can change this for the CDX700U to gain iPod control.
In the end I put the Sony head unit into the boot, it's held onto the underside of the parcel shelf in an enclosure. My car had originally had speakers mounted on the parcel shelf - I replaced these with a nice period looking set of Blaupunkt speakers that I'd bought in the early 90's but never used.
The aerial in my car was a piece of junk - so has been replaced with a Hirschmann whip - but a retractable Hirschmann 6000 F1/11 is on it's way. And for the DAB we tried one of the adaptors but it's junk - so it's been replaced with a Bloomice glass mount pad antenna which is ok.
I'll post some pictures when it stops raining! But it looks wonderful and very original - all the modern stuff is hidden from view - even when the boot is open.
You can't get away from the fact the Tadpole solution is not cheap - but for me it's worth it to have DAB and MP3 CD playback in my Coupe ;-)
Philip