Potential rewiring for heat pump
I am looking into replacing an old heating/AC unit (electric, but not heat pump) with a new 3 ton heat pump. The current unit has 60 amps dedicated to it and there is no empty space on the panel. My understanding is that with heat pumps, the outside condenser and the inside air handler need more than 60 amps combined to run when it is sufficiently cold outside (because of the heat strips in the air handler).
The outside unit is on the opposite side of the house from the panel, with the air handler in the middle. The unit is on the first floor of a two-story house. My first estimate for the upgrade was $2500+, which includes adding a subpanel for at least 2 - 30 amp breakers and running new lines from the box to the air handler and then to the outside unit.
First, is my understanding/explanation correct? Second, if so, is this all necessary or are there other options? Third, if it's necessary does the bid sound reasonable?
Thanks for any advice on this.