Here is the hardware list:
http://www.x-h2o.com/threads/12377
You're looking for M8x1.25. Stock is 30mm long, so if add the length of the keeper to the stock 30mm you should be good. If it is a little longer than you need, just pick up some extra washers to stack under the head of the bolt.
edit: the chart has the kenny keeper length that is needed.
And try a set of bed plate to engine mount bolts, I bet those would work for you.
You're lucky. Ace is the closest hardware store to me, but their stainless selection is the worst.
Do it Best is a little further away, but has the best stainless selection. But I'm also lucky b/c I have a grainger and fastenal right down the street from my work. But they are only opened on weekdays, and it seems like you always need random hardware on weekends or in the evenings.