"In Search of Mustangs" isn't an organization, but rather a project intended to develop a database of all known Mustang door tag information through voluntary reporting. They eventually published two volumes based on their research, though the usefulness of the post-1967 data has now been largely usurped by Kevin Marti's acquisition of the Ford production records.
On the bright side, Volume 2 *does* list 8T02C118095, giving the last known owner as Timothy A. Marki of Ohio, though this could have been entered into the ISOM database anytime between 1984 and 1994, so it's hard to say how accurate or helpful it would still be. It does suggest that a registration search through the Ohio DMV/MVA might be in order, however.