I have good luck stuffing sealed/gel cell batteries in old cases. See my report on my Harley KHK battery. My bikes are kept in an unheated building and the batteries require a short charge every 6-8 months. They last for years. After all, these batteries were designed for emergency lighting and were expected to sit for years with little use. My voltage regulators are fairly precise*; so, there has been no over-heating problems, even on fairly long trips at extra-legal speeds. When the time comes to replace inserts, I'll try lithium ion batteries. I see no advantage in using a nasty old original design that can run dry, have a short life, require greater care, and puke battery acid on a nice old bike.
*'48 Chief has a Bosch generator/voltage regulator from an old VW
'56 KHK has Cycle Electric 6V electronic regulator
Indian 841 has original generator and regulator
Last edited by Coolbreeze; 10-31-2012 at 11:23 PM.