I'm fairly new to Pontiacs, so I could be wrong, but I think the same blocks were used for R/A and non R/A engines, at least in 1970, where this block originates from. Different bearing caps (2- or 4-bolt) were obviously used.

My block has casting number 9799914 and YS as the engine code. That translates to a 1970 350hp GTO without Ram Air according to these pages:
http://www.pontiacpower.net/engcast01.html
http://www.pontiacpower.net/engcode01.html