I can well understand why you would retain the original engine on what is a collectible mower. With regard to your engine, you might care to take a look at these two threads, if you have not already done so:

https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=37736#Post37736

https://www.outdoorking-forum.com.au/forum/u...amp;Main=7046&Number=36218#Post36218