Hi Michael, no mate, it is not the original engine on that machine....IMO that engine could be off a Scott Bonnar Model 720 (72104); a Model 520 (520022) or a Model 420 'Huntsman' (420400)
Check them out HERE
That engine was manufactured on the 14th August 1975. wink
cheers2

Please do not PM me asking for support. Please post your questions in the appropriate forums, as the replies it may receive may help all members, not just the individual member.
Kindest Regards, Darryl grin