Old heating and cooling to central HVAC conversion cost

[Chalew Stock]

Hello BP community,

 I'm interested in a two-level house with the following combination of heating and cooling systems. The upper level is heated by radiators and cooled by central AC, with additional use of window units. The basement is currently not heated, relying on window units and plug-in heaters. There is also an extension room that utilizes a heat pump. Considering these different systems and the total area of the house, what are your thoughts on the overall efficiency and effectiveness of this setup? 

Additionally, if I were to explore options for improving the heating and cooling systems, what suggestions or estimated costs would you recommend? I value your insights and expertise. 

Thank you.