Get one of these. I did.
http://www.harborfreight.com/power-t...dle-65570.html
When you order or are at the store, get a blade pack that has the long wood cutting blades. Coarse tooth configuration, with PLENTY of some sort of oil. It'll take several minutes, but minimal shavings. I cut through one of these machine weights across the width in 5 minutes. it's 2" thick! Weighs 90#.
A circular saw creates a LOT of shavings. AND when/while they're coming off the saw, they're hot and hit with force. Remember you're creating a large lead contaminated area with fine lead shavings.