I think that the most usual pots (the ones you'll get from a hardware store without specifying number of revolutions) have a 300 degree spin. If you can find their middle position and attach the servos on them, then you know that you can have the servos go from 180 (which is their starting point) down to 30 and up to 330. I guess a bit of trial and error will work there too.

Do you think? OK, I'll try it out. Maybe you're right. Thanks to you all, guys! Helped me a lot!