Road Runner Nest

Hey nest. I need some clearification on a 440 engine numbers. So, if anyone can help, I'd appreciate it.
I'm looking at a 440 engine with i.d number of 2536430-9. I know it is a 440, but what does the -9 mean?
Also, it has the numbers 2 12 HP A. I know it is a HP motor and the 2 12 is the date made(?) but what does the letter "A" mean as well?



Thanks again!

Just a guess on the -9....would it be the casting mold number? Obviously the had more than one mold at the foundry...
I believe the A on the machined pad near the distributor means an 0.20 oversized cylinder bore.