I'm going through the same thing on my car right now. Mine was due to the wrong gear material. The guys at hardcore5.0 were helpful, go here if you want to check it out:
http://bbs.hardcore50.com/vbulletin/...threadid=12769 . There is a pretty good link in that post too. After checking my block I can vouch that not all blocks are the same dimension. The dimension MSD gives would err on the safe side in my case, but I can see how it might not work in all cases. After taking off my oil pan I would highly reccomend that you do the same thing, it is the only way to properly clean out all the chunks and shavings. If yours is like mine there will be pieces up in the motor too. You probably don't want to hear this but you better take a REAL good look at the teeth on your cam because they are more than likely chewed up too, I just had to order a new cam today. Hope this helps some.