Yes, the original is an 18.5hp Intek. Been digging around. I believe I'm going to go with a Briggs and Stratton 44n677-0011. It's a 724cc 22HP engine. Not those fake John Deere 7 220 engines which are 656cc but claim 22hp even though every Briggs and Stratton labeled 656cc I can find is 20HP.
I upgraded my transaxle to the K57R.
Everything looks right for this engine. Crank is the same size, same amperage alternator, has fuel pump and electric start. Everything I can tell about the above engine would work in an L118. Which as far as I can tell uses the same frame as the L108 (my mower). My frame also has the cutouts for the second exhaust and larger engine mount spacing.
This would be a lot easier if searching engines was easier on the Briggs and Stratton website. But they don't list every variant. Just a few key models. Rather than having to dig through their site and various small engine sellers.
I think the only other thing than the engine and exhaust I'll need is a longer throttle cable.
I'd just appreciate a sanity check before I order.