Thats the SAME EXACT mower as my dads! except my dads is a 210. that mower is a BEAST because of the huge horizontal shaft Kohler engine and how heavy it is. i mow with the 210 and i'm terrified of it when i'm going only 7Mph! i cant imagine ever going faster on it!. if your going to make that mower faster, i suggest you take changing the steering into consideration, because the stock steering has too much of a steering lock(from straight wheels to fully turned is 1 1/2 turns of the steering wheel)and the stock set-up breaks Real easily, and you dont want that when your riding along at 40 Mph!
If i were you, i'd make that mower a Pulling mower because #1, it'd blow all the other pulling mowers away in pure pulling power, #2, going any faster then 15Mph on that mower can be REAL dangerous because if you flipped it with its weight, it could crush you and injure you severely. and #3 because the parts for that old of a mower are VERY rare.( the muffler on my dads 210 went shot, so i went online to try to find a new one, but i could only find one that was sold already, so i had to repair the muffler with a coffee can!)
