How much is an incumbent GP worth, when they come as part of the deal?

Dear Aunt MASie

We are a group practice and we’re looking to purchase the patient-base from a nearby solo practice. As part of the transaction, the current GP owner will continue to provide GP services to his patients from our rooms until he retires in a few years. We’re not sure if we will engage him as a contractor, or employ him for this period. Can you give us an idea of current market rates paid to GPs for both options.

How much for a GP? Wellington