G'day MF,
Dunno about being 'prized', but this one's the 1980s pushrod OHV engine. This one has been 'rode hard and put away wet' a lot though - rusted up muffler nuts; low and black oil; etc.
Edit: A couple of pics of the 'donor mower';
https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/54597/re-vulcan.html#Post54597I have the well maintained 4hp IC series Briggs from my original Big Bob to use on the 'frankenmower' to be built from the combined bits, so the Honda is excess to requirements, really.