Battery technology has significantly improved since the 1950's. Pretty much any group 2 battery will serve your needs just fine. Just make sure you're getting a fresh battery-- not too many people buy 6-volt batteries anymore, so it's quite possible to get one that's been sitting on the shelf for a while.
Your best bet might be to buy it from a high volume retailer (think parts houses).
I've installed countless batteries from NAPA in customers' cars as well as my own, and have always had good luck with them, especially considering they're reasonably priced. Go with the one that has the longest free replacement if you're buying over the counter at a parts store or online.
This is the one I have in my '52, it's been in there for four years, and it still tests good on both load and recovery.
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Battery-Automotive-Commercial/_/R-NBE7204_0398748037This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=142154