Waveski,
Short answer in a nut shell is yes, you can continue to use your 6 volt "stomp" starter on 12 volts, but it's best to make sure and limit your starter operation time to as little as possible.
The 12 volts will spin it up faster, but will also cause excessive heat and wear if you crank on it for extended periods.
There are a bunch of previous conversations on the subject. If you are interested in reading more, use the
Search the Stovebolt site tool.
I entered "6 volt starter in 12 volt conversion" and got a list of several on-topic posts that can help explain more details on the subject.
Hope this is helpful.

Dan
