Scott knows these drives better'n me, but I have the 140 and the 120 uppers with different ratios (19.20 & 16.20 respectively) like I put in your other topic. Lowers are all the same (15.23).
BUT - the 980308 number you have listed is one I can't find. I think it's the part number of the upper gear case housing, but I can't confirm that. So, I wouldn't be too convinced you've got the 140 gearing just yet. The difference in gear ratio (I think) is slight enough that you can re-prop if the boat doesn't perform well. If it turns free - run it.