looking for 68 302 MO block and crank (vin 465803)

[jims68z]

I am sure this is a needle in a haystack but I am looking for that original motor.  the last 6 digits of the car are 465803.  If I can not find the original block, I would like to find a replacement.  I purchased a motor for the car and just found out the block and crank are cracked.  I have everything from carb and intake to pan and almost all accessories.  I just need a block and crank.  can anyone point me in the right direction?