Hello Shad, I am hoping that things are progressing for Ryder, I continue to pray for him, you, and yours.
On the engine thing. Have you looked to any tractor salvage places for one? Massey Ferguson tractors used a great number of the 153's, if you have access to the "Capitol Press" you might be able to locate one through them. I believe some of the Bobcat skid steer loaders and quite a few genset applications had that same engine. There have been a fair number of them that were used in the marine industry, but they might have considerably different cooling system, exhaust, and intake set-ups. Just a thought if this one doesn't work out. Best regards and God bless, Allan