I believe the Pleasant Township NW corner Gwynne farm is the lower farm just NW of Mt. Sterling. I find the Upper Gwynne farm listed in Deer Creek Township which is north of London, Ohio and just north of Lafayette. Other notes:
A farm worker, Herman Reichelderfer,was found dead in a field onn 13 Oct 1993 on the Lower Gwynne farm by then farm manager William Murray.
More recently in 2010 Carl & Nancy Hamman managed the 3,000 acre Lower Gwynne Farm per a couple of agricultural magazines.