Unfortunately uncirculated 64 halves aren’t worth very much, because the combination of emotion about JFK and the end of silver coinage caused a lot of people to stock up like your father did.
I avoid silver coins that look like regular coins, so no silver kennedy halves, roosevelt dimes, and washington quarters for me.
Last time I bought silver coins about 6 months ago I got 100 mercury dimes for $150. They’ve started to become popular with prepers as they are the smallest and thus most practical silver coin people will use after Obama declares martial law and hyperinflates the dollar.
Franklin halves barely cost more than melt value and might be the best US coin to start collecting.
The down side is you either have to get them online and worry about insurance and credit card and shipping fees, or else buy them from local dealers in transactions of $1500 or more to avoid California sales tax.