thin cylinder walls on a 440?

I was wondering in anyone had any info as to a rumor I heard about some early 70's 440 blocks having thin cylinder walls from the manufacturer? My plans are to build a 440 blower motor and this would definitely be something nice to know. I am in the Marine Corps and currently in Afghanistan trying to get an idea of what all to get in line for the block I have. I haven't had the chance to get it to a machine shop to be checked out yet, but my block is a 72 and am wondering if I should begin looking for another starter block.