Thanks everyone for the replies.

Pywallet seems to dump the private keys and associated addresses, so I should be OK. I found that they is a --dumpbalance flag, but it seems to timeout or not work on most of the addresses. Looks like there is about 100 or so addresses per file, so I could eventually enter them all into a web tool to check their balance. I don't want to download the entire 140GB blockchain file if at all possible, but that might be the easiest way.  Years ago I remember it took weeks to get the much smaller blockchain download because it was so slow through the peer to peer network.

Is there an easier way to download most of the blockchain file at once now? I have a 100MBPS internet connection and lots of space on an external drive, so I could go that way.

It is all rather stressful now that I realize that a screw up would be tens of thousands of dollars worth of mistakes.

Thanks again!