turboh224g

I am relatively new to sr's but have pretty much general engine knowledge. I have built several turbo honda setups for myself and friends. I have recently picked up 3 cheap sr blocks that all need rebuilding. On all three the problem was in #3 cylinder. I have also read about several other people having problems and is seems to be the #3 cylinder most of the time. I am curious to know why this is? More importantly what can be done to keep this from hapening and result in a reliable rebuilt sr? Any help would be greatly appreciated. Thanks,
JKP