Advice needed - new Carrier AC system for our home

Seeking some advice / feedback on a quote that we just received for replacing a 25 year-old AC system in our home. Some background:

We live in the greater Los Angeles area. So temperatures can get >100 degrees in Summer and early Fall. Our 2-story home is circa 1905 and has all original windows and very little insulation. It is a historic landmark and so along with the beauty of our vintage architecture is the reality of inefficient single-pane windows, lots of spaces for air leaks, and so on.

We had AC installed in 2001 - configured as 2 zones (one for first floor, one for 2nd floor). We need to move the condensors to make way for some landscaping we are doing. Local company (lots of good reviews / well known in our area) has provided a quote to install 2 new compressors. Also provided the option of installing a 2-stage system instead of single. We have natural gas heat as part of the system on the first floor and that will not change. No heat upstairs (don't need) - so they will update the air handler up there completely.
Here's the detail on the quote:

New R-454B equipment. Proposal To replace and relocate (2) condensers and replace (1) attic fan coil and (1) cooling coil. 1. We will pump down or recover refrigerant from the (2) HVAC systems. 2. Cut refrigerant lines at ground level and leave in place for others to remove. 3. Replace condensers with (1) LENNOX ML14KC1-060-230 and (1) LENNOX ML14KC1 048-230, units with new pads on the West side of the home. 4. Replace attic air handler with (1) LENNOX CBK45HVT-048-71 horizontal fan coil in place of the existing. 5. Install new secondary pan if needed and install any required sheet metal transitions to connect to the existing ducting. 6. Install (1) LENNOX CK40HT expansion valve equipped cooling coil onto the existing CARRIER horizontal furnace located under the home. 7. Install new insulated copper refrigerant lines and cover where needed. 8. Relocate 230-Volt power and low voltage to the new condenser locations. 9. Complete all required connections, evacuate and charge. 10. Provide permits and HERS certification. Total: $28,681.50. WARRANTY: 10-year parts, 2-year labor

They are also offering a 2-stage upgrade option"

OPTION for high efficient equipment: #1 Substitute (2) LENNOX ML17KC2, two-stage condensers with CBK47UHET fan coil and CK40HT evap coil: $32,787.27. Same Warranty.

Appreciate any feedback on this - in terms of the single or two-stage unit as well as the equipment being proposed and the pricing.

THANK YOU!