Looks a bit like Aguirre, although it's a bit unusual to show a pitcher hitting.
If not him, maybe career minor leaguer James Armstrong? He was in the Cubs system in the late sixties, so maybe. Only pics I could find to compare were these two team photos: 1969 Indianapolis Indians & 1971 Trois-Rivieres Aigles, which were both rather inconclusive:
1969 Indianapolis Indians 8x10 Team Photo Vintage Baseball Cosman Carbo Nolan | eBay
http://quebec.sabr.org/photo_1971tr.jpg