Installation guide

ShoreTel Voice Switch Feature Capacity Planning and System Design
2
ShoreTel 14.2 Planning and Installation Guide 41
You would have room to spare:
HG 1 + HG 2 + BCAs = Total
4 x 4 + 8 x 3 + (10 x 4)/2 = 60
16 + 24 + 20 = 60