The numbers thing can be terribly misleading, most anything could have been done over the years to the block and other components.... Very easy to check the bore and stroke before you dissassemble it. If it's just a bare block, then just measure the bore and probably also check the dimensions on the cam and crank journals....Who knows what's been done there??? If it's dimensionally what you want, then have it tanked and mag checked. Then build it....

On a street type engine, I don't really think it makes a whole heck of a lot of difference what the nickel content is, street use won't stress it much anyway...

Another consideration before you waste a lot of time searching for a block, then having it cleaned and checked, then all the machine work remember there are a number of companies along with the OEM manufacturer that offer brand new blocks that are superior to the production pieces.... No sense to spend a bunch of time and money, reject 3 or 4 blocks cuz someone has already been in there and mangled a few parts or performed some questionable machine shop practices, then spen all the money for maching everything when a brand new block can be had for under $2k..... Ask Pat or one of the other machinists what it costs to do a block up so that dimensionally it is equal to a new one.......

It's not always about how much $$$$ you spend, but how you spend it.....