Pic of the bottom? Might help to reverse image search, that can be one of the most "obvious" parts to match.
The primer on the fuel tank implies Kyosho or Tamiya, but little else about it does.
The Sh.18 engine is likely not original, especially with that aftermarket flywheel. The clutch bell is HSP, so it's geared in 1.0M... It kinda looks like 1/8th scale, but that engine would be a bit overtaxed moving that with a 2-speed; maybe it originally had a big block. Could be a bit of a Frankenstein.