Hey guys, I'm new to this so I guess I'll just post my question. I purchased a SB Chevy engine a few months back, running engine minus carb,it had a set of camel back heads on it that supposedly were original to that engine. The # on the back by bell housing reads 2970010. Below that on the actual back of the block,hidden by fly wheel it has the numbers 0.10 & right below those are the #'s 0.20. I've been told those stand for an additional 1% Tin and 2% Nickel to strengthen the block. Can anyone shine some light on this subject and maybe have an idea what this originally came in. Oh...the # on the front of the block by pass side head is V0210TBX. I'm lost, thanks.