I'd say his range is good 7s, two pair, or a set.

Board: 7h 6h 4c
Dead:

equity (%) win (%) tie (%)
Hand 1: 71.5342 % 65.68% 05.86% { 7d6c }
Hand 2: 28.4658 % 22.61% 05.86% { 77-66, 44, A7s, K7s, Q7s, 74s+, 64s, A7o, K7o, Q7o, 74o+, 64o }