Hi, JRoss,
I'm no decoder pro but it looks like your car maybe was manufactured on Sept. 22, 1971. Yes, it is an early car. If you still have the sticker on the door it may read 9-71 for the date above the VIN. I don't know what's the date of the 1st '72s made but I would suspect early August.
From the fender tag I can't tell much else about the engine except the fact that from the factory in the "H" (2nd digit in VIN) cars the 340 was an optional engine ordered that way from the tag.
I'm sure there's someone that knows how to tell the high and low compression engines apart by looking at it externally.
They both possibly had "J" heads but the "J" heads I think had both the large and smaller valves in them so that's not a good way to tell.
Starting in '72 they started using Electronic ignition on the V-8s but I guess they could have put Electronic Ignition on a '71 engine.
I dunno?!?!