Install Ginger Yoshi 1.4 on HTC Magic 32a, which radio do I need?
I now have GingerYoshi 1.5 running on my HTC Magic 32a, so I'll answer my own question and explain how it went.

As for the radio 6.35, answer is YES, you can use it with the GingerYoshi for 32a new radio.

Here is how I swithed from 2.2.1 CM6.1 radio 3.22 to 2.3.5 GingerYoshi 1.5 radio 6.35

1) I reverted my HTC magic back to the stock rom 1.5 + sense, this to simply revert to the new 6.35 radio.
I did the update by connecting the phone to usb and running the RUU
RUU_Sapphire_HTC_Europe_3.05.401.1_test_signed_NoDriver.exe

2) Then I had to reinstall a recovery, as we have radio 6.35 we need a Hero recovery, that is amonRa 1.6.2 for hero (the 1.7.0 wont work with magic)

3) I flashed 1.76.2007 SPL

At this point only thing left is to flash GingerYoshi.
From recovery, do a full wipe.
(I didn't care about having an ext partition, so I left my sdcard untouched)

4) Flashing "ginger yoshi 1.5 new radio 32a.zip" from recovery

following install procedure, answering the questions in order:
- no ext
- zeam launcher
- no swap on ext
- big density

REBOOT:
new HTC logo with hiding bugdroid

Enjoy GingerYoshi 1.5 and Android 2.3.5, so far everything seems to be working fine, and no more troubles with my simcard. Quadrant now gives 387 instead of 299 with CM6.1 :-)