Charley,
It could very well be that what you have is a replacement block, which wouldn't have had an actual vehicle serial number stamped, but could have been stamped at time of purchase/replacement to match whatever the owner needed it to.
It would certainly appear that someone did go for the "848" head mod, or could have been just a replacement out of necessity if the original head became unusable? Can only guess from what is there.
looks like you found a "keeper"!
Dan
