Looks all original to me, 1978 Victa Contessa.
These were the lower bracket at the time, and were one of the last Victa Low-Arch's, along side mowers such as the Victa Commodore and Wild Cat of the era.
At this point, most low arch's were store-brands, like the monaro, however, rather than siphon off the entire low-arch market to the department stores, Victa retained a few mowers, such as the Contessa low-arch, under it's own branding.
Many of the late 70's Victa low arch mowers were also available as hi-arch, I know the monaro was, and i recall this Contessa also having a hi arch counterpart.
I don't know if the sticker is there, but I would guess this to be a V-189, or a WY-163-A9, if it is still there, this number would be located on top of the air filter lid.
The carby should be a G4, rather than an LM, however, I often find they have been 'updated' at some point, usually this happens after the decompresser nipple is snapped of the back of the carby during repairs.
Finding another base for that should not be too hard, that base was the standard mid to late 70's low arch store brand base, used on a large number of mowers, you could use any, and simply put the right sticker on, if you can duplicate or transfer the original.