http://www.analoguerenaissance.com/D5534A/
At 25 Euro each, they are pricey.. but the 80's tech should interface well.
The Juno-106 is probably the closest "real" ramp/saw wave you can get from 80's tech DCO's.
It might not be too difficult to figure out how/what he used to make his MC5534A clone and configure it for physical use in a Poly800.
This guy gives a good explanation of a MC5534A chip.
http://www.electricdruid.net/index.php?page=info.junodcos