SAN HOSE
San Jose

Not so sure that the type of compressor was related to the engine size or type but more likely IMO what company typically supplied a particular car assembly plant. Because of that we might have a better or more accurate idea if we knew when your car was built/completed at San Jose.
Of course a lot of R codes were built with 4 speeds so no AC but there is are pictures of a AC equipped in the 69 Unrestored Picture Thread section titled
69 SJ R code Mach I - Unrestored Picture Thread that shows a cast iron Tecumseh compressor. April built car