It's a 340 from the casting #, but the stamp at the front of the block only appears to have these #s.
I was expecting to see something like "FW340P2940009", though this engine # should start with G ('71) or H ('72).
Casting date is messy, but I'll post it, and lean on the braintrust here...

Not enough info, so some tips;

Clean that whole pad of paint.

Get a photo of the partial VIN number.

Post actual photos also, not screen captures. The image quality is dismal with those.

(No H series for LA, 1971 (G) was their last year)

^^^ When I say "LA", I mean engine family; I refer to Los Angeles assy plant as L.A.
Gonna clean the whole area and hope the rest of the #s show up, but there's not much room left.
Photos are phone-to-phone-to my PC.
The concern is whether it's from model year '71 or '72 so the owner knows what he has - he's been told both years...

Any of that era LA motor (as compared to the later model Magnum small blocks, or the earlier "A" motors) has the size of the motor cast into the block on the left side of the block near where the starter was located, (*318* ,* 340* , or* 360*) in raised numbers. Its pretty easy to identify the block by the raised cast in numbers. Some of those raised cast in numbers are pretty hard to read as well, but its pretty easy to determine the difference between an 18, a 40 or a 60.
The numbers stamped on the pad were numbers stamped at the completion of the machining process, and many of those were really low quality stampings (particle numbers, weak nearly impossible to read stampings) are not unheard of.
If the block has been cut, some or most of that stamping may be gone. With this many years gone by, its possible the motor is not the original to the car, it could be a different motor from the same time frame, or it could have even been a replacement block someone stamped themselves at some point. I'd be pretty suspect about a motor that old with that much shiny paint, unless the rest of the car is also pristine original.

Edit: As I read the casting date, I see a casting date of 11 of 71 on the 2nd shift. Should have been a 72 motor.

Looks like a 2 preceding the 11 which would be 2-11-71. that would make it a 71 or later motor. I 've seen some cast 2 years ahead of use

Yeah, I do know it's a 340 - saw that in another photo of the side.
Now the casting date looks to me like 2/11/71, with clock below it denoting when. Right ?
FWIW, I'm 2 1/2 hours from the engine - just trying to help the owner figure out which spec it is.
Intake manifold has been changed, & maybe the carb and/or single-right-side air cleaner - both intake & air cleaner are orange.
Might have to look for VIN on pan rail, but the front info on my '74 was in a line.
There's an interweb photo of one with the info on 2 lines, so more sanding, I guess.

Haha, TJP, hopefully we're Great Minds
Agree on casting vs actual build/usage dates.

Had a 413 in my 64 300. Cast, built and stamped as a 63 motor, with the T (for 63) overstamped with a V (for 64).

Original motor? I dunno, remember no VIN stamp back then. But it wasn't an anything special car with a need for numbers matching, I bought it in 88 before all the numbers matching craze hit. My theory is they built more 413's for 63 cars than they needed so they restamped the left overs to put into 64 cars.

It definitely was not a 64 motor, 4 bolt valve covers, rocker arm pedestals. etc.

Mopar lowered the compression ratio and change the valve sizes on the 1972 and 1973 340 motors, they still ran good

Cast cranks were also substituted sometime in the 72 model year and thereafter

Dat be very true

And external balancing.