Same with mine, I still call this a series 70 though, because in technicality it is.
The series 70 was released in 1970 and went through 4 generations, MKI (no decomp), MKII & MKIII (Decomp & G3) and MKIV (G4 Plastic Carby & Decomp)
Toward the end of the 70's (I believe somewhere between 1976 and 1978) they started to call them series 80, in the lead up to the 1980 release of the actual Series 80 engine (Geared side start)
The 1980 side start with points was deemed the MKI, while the later electronic ignition version was the MKII, the Series 80 you have there was never given a designation, as it was not considered part of the official lineup once 1980 rolled around.
A few machines continued this top start series 80 into the early 80's, but only for a little while, and only some very limited models.
The engine on your tiltacut generally gets many names among collectors, some call it the S80 prerunner or forerunner, some the S80 MK0, and some call it S70 MKV.
I tend to call it a series 70 MKIV, as the difference between it and the actual MKIV comes down to the sticker. calling it this also helps distinguish between top and side stat Victa full crank engines.
