Bill Q,
It is certainly not my intention to steer your wrong, so please wait for, or seek confirmation from Ira - or send him a PM and ensure that the member list is acceptable for an extreme ride like the 100CCC ride. There are other rides that need to be done and documented with the IBA before attempting the 100CCC as this is considered an "extreme" attempt.
Ira represents the IBA as an officer of the organization. I am just a member and NOT an official voice in any capacity for the IBA.
This is the official list for IBA members who have volunteered to be witnesses for the Saddlesore 1000. They would be ok for the 50CC since the rules are very similar for all those non-extreme rides.
http://www.saddlesore.com/witness/witness.htm
However, the 100CCC is a completely different story so do check with Ira to ensure he, and the review staff are comfortable with these folks acting as witnesses before you begin.
Mike