I'm trying to figure out if I have a 361 or383 in my Windsor. Engine block casting #2128854-5 comes up as a 361. Engine pad below dist. has R38 stamped with a diamond and a little zero beside it and a 6-20 below that which comes up as 383. Am I correct in saying it is a 383 with the block casting saying it's a 361? Which is it?

 

in 1961 windsor could have two different 383s, one was a long stroke short bore. one was short stroke long bore. the long stoke is 3.75. short stroke 3.38. cant remember the bores. the 3.75 stroke is one of the fewest ways to get a 2 bbl intake that fits a wide block like a 413.