Vintage ESC motor limit?

[VintageRacer]

I have a vintage Nosram ESC; Advanced FET controller, I think it was called. It was Nosram's first product launched in the 80's.

It was the previous version of this:
http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWA:IT&ih=017
(the only difference was mine has a heat shrink case rather than the nice hard plastic case).

I've email Nosram but it got ignored so I'm hoping someone here knows what the motor wind limit is on this as I only ever ran it with 27 turns in the standard class.

I have magazines from the period stating some people are using as low as 16/17 turns or so, but these are old motors and also using old cells.

I'd like to know what modern equipment I could use it with without melting it.