Bought a 67 R/T with a running motor and the "original" block. Have driven the car for two seasons and now I decide to see if it is or is not. Car was built in 5/67...block is 12/66..front pad stamped c440hp
I was under the impression, 3 months is the window but some have submitted 6. Any experts out there know ? Thanks in advance...thanks moparts

I have a 340 with a block that was cast in January 1971 and went into a 1973 STL car.

There is no window for the casting date. There might be a window for engine assembly date but even that would be suspect.

Mopar was horrible at inventory control during the 60's and 70's. Lots of engine blocks sat around for months (years) before being used.

That is totally within range to be correct for your car. The key is the stamping date and codes on the ID pad. So far it looks to be correct for your car but you need to post more info.

So far you have posted C440hp

C-1967 Model Year, 440-CID, HP - High Performance

Then should be a date using month and day of month (which typically predates your cars SPD by a short number of days) then there will be a build sequence number (example: 5 would be 5th engine built that shift, etc.).

What is your cars SPD?