There are some additional rules for the cycling events here --

http://www.smsg.org/senior_games/spo...fo.asp?Area=CY

From what I can tell, this is not a USAC-sanctioned event, but the promoters say they will follow USAC rules (with the exception of fixed gear). Interesting that they are allowing recumbents but I couldn't see a separate HPV category.

Anyways, my gut feeling, although I couldn't find this in writing, is that you need a traditional road bike with a drop bar. But don't let that stop you! I'd say email the promoter to verify this and then get a bike and keep training. What a fabulous goal for you.