What are friends for? A long, long time ago, a friend, also an apprentice mechanic put my brakes on backwards. When they made noise, he told me to get speed and slam on my brakes to seat them. Did a really nice job on my freshly turned rotors.
It's not like you need a head or the rockers. You have to be able to find something. I have had reverse fine thread bolts made for me, in the US, and it wasn't that much money.
There are a bunch of Studs on E-Bay, under Yanmar studs. But it makes me see that going to a marine source might work. Also, forget about JD, Any rebuilder that does Yanmar should know a source for the studs.