A 970 gas 8 speed seems rare to me to the point that it may be a collectors item some day.
I know you said you wanted a pulling tractor and this is just my humble opinion but I personally would consider keeping the 970 gas and restore it to its glory and finding an old 930 gasser for the pulling tractor.
This is just my opinion.
Please share some pictures of your tractor I would like to see a 970 gas.
I donít think I have ever seen one