Yes, you need to be careful with press release & sales brochure shots, because many of these cars are built months before the official release date & are often made using previous models altered with a few bits added.
A famous one is the HX LE brochure. It has many HJ pics because the pilot car was actually an HJ.
This one could be the same; LC m/cyl, LC heater box !! What about the carby fuel lines ? Are they 186 XU1 style. I always forget, were the LC fuel pipes used for early LJ, or were the LJ style fitted to late LC ? What I mean is where rubber hoses were replaced by tailored steel pipes.
Getting back to the square-ended m/cyl, the simple fact is that the LJ style including the booster with the different pushrod, was introduced in HQ production in July 1971 & this carried over to LC production, so by Aug/Sept 71 the rounded m/cyl was no longer used. In similar fashion to the Opel M20, it too was gone by that time. So, if you had a pic of an LJ XU1 with an Opel box fitted, we know it can't be correct, unless it was an export special or similar.
The lack of the brake pressure differential switch block, this makes it a very early 1971 at the latest !
Steel carburetor fuel lines were introduced roughly 4th month 1972, early junction block the pipes are joined like a silver solder, compared to the later, brass "threaded fuel block & the early pump to junction block has a brace near the centre carburetor area.