G'Day Ruairi and welcome to the Forum.
The numbers you have posted are only casting numbers from the foundry so they dont identify your engine. On my twin Lister there is an id plate to the right of where your fuel pump is and possibly up a little bit. Plate is around 2-3" wide and 1.5" high. This is what you need to turn yourself upside down to find ir better still give that job to your son. It might be a bit easier to find with those air ducts removed.
At least it looks clean and tidy down there so that is a bonus. Is it in running condition and are there any problems with the engine?