Since so many of us are on strict budgets or just have redone your drums I was going to order new drums for my 64 El Camino from POL and they have an option now for cross drilling them. I Googled it and came across this article:
http://www.chtopping.com/CustomRod4/ which was interesting because 15 years ago I drilled mine for the heck of it when everyone was telling me I'm nuts.
It works...might drill my brand new drums for the 65 GMC now too.