Like Dale said, the starter bolts will be "12-point" wrench or socket. The bolt heads are 16mm.
There are many curved, s-shape, and swivel sockets available to get into tight spots. IIRC I was always able to get the bolts loose with a socket and extension (maybe I used swivel head or wobble-ned extension). Be careful, those starters are heavy.
The bolts should have lock washers - so loctite compound not needed.
Here's a pic of a typical C12/C13 starter. Is this what your working with?