I think I also see the WT stamp running about 90 deg from the other stamps. WT = water test. Curious about all the different numbers toward the bottom.
My 66 HEMI block has a 10 29 or 25 on the bottom and I think that's the build date. Since my block is cast Jan 18 66 then I have to assume the assembly date was 10 of 1966 and installed originally in a late 66 car?? Normally I would think a build date of 10 66 would go into a 67 car but perhaps I would have a CH 426 on the pad instead of a BH.