New air conditioning system ideas for 100 year old single-family

[Mike Nelson]

I would like to have a new central air conditioning system installed for my 1,800 SF  100-year old single family victorian-style residence in Oak Park, IL.  The home is a two-story, with a full basement and a full attic.  Currently, the home has a good hot-water boiler-radiator system for heat located in the basement.  For cooling, we rely on seven window unit air conditioners and free-standing window units.  It is an annual back-straining exercise to remove and install these units every year.

My thought is to go with a high velocity system with 2" diameter tubes for distribution.   There would be one or two air handlers and condensers.  I hear the term "SpacePak" around the neighborhood.  Apparently this is a brand name, there are competitors.  Are there any ideas on solutions, as far as types of solutions at the most reasonable cost?  Is there a less expensive time of year to have this done?