according to Sportrack - the Sox payroll is around 159M. That gives them around $61 million to play with, even after assuming around $10 million in arb-eligible salary increases. If this is accurate --- they can pay Monty without breathing on the salary tax limit.
https://www.spotrac.com/mlb/boston-red-sox//payroll
https://www.spotrac.com/mlb/boston-red-sox//payroll