GO WITH 200 amps it coists a bit more but is a sales feature at home
resale time. get the largest panel number of slots available. just
think of how electric has changed over the years, be prepared for the
future.

do finish the upgrade to ALL 3 prong add GFCIs in appropiate places
like kitchens bathrooms basements etc go with arc fault for bedrooms
and such.

do it right do it once and enjoy your new AC

incidentally I upgraded from 60 to 100 amp service years ago, BIG
MISTAKE I should of spent the extra 75 bucks for 200 amp service.......