have 105 sti 8spd shifters.
Scirrocco wheels with campag hub.
Veloce 9spd cassette with spacers and 1 cog removed to be compatible with the 105 sti.

I need a new rear DR for about 6 months before changing to all Campag Chorus drive chain and Chorus 10spd Ergo.

Which RD would give me the best shifting in the interim?
1. 9spd 105
2. 9spd Ultegra.
3. Used 8spd Durace if I can find one.
4. 9spd Veloce
5. Used 8spd Veloce if I can find one.
Any other suggestion?
Thank you all for your time, much appreciated.
Bike is Carrera Nivachrome, in A1 condt.