327 small or large journal?

I have a 327 I pulled out of a chevy truck I bought, I got the casting off the block 3933180 which from what i can find is a 68-69 large journal block.

I pulled the pan on saturday to see if the crank was forget or cast,it was forged but when I looked up the casting number 4577 it came up as the 62-67 small journal crank?? The crank also had a big R stamped into it idk if that matters or not?

I even got the date code off the block D 10 8
Thats april 10 of 1968 right?

I just cant figure it out why there is a small journal casting 62-67 crank in a 68-69 large journal casting block

Anyone got any ideas
The guy i bought the truck from said the engine had never been apart it came out of a car his parents had...and it sure didnt look like it had

you need to measure a journal---2.000 or 2.100---------