The OP said he’s running it without the shroud and tin covers.
“I've been down that road, doesn't seem to make much difference. I have the whole grill and fascia out to keep more air on it. Need to pull the engine out to replace the rear main and it's low on my priority list, no oil leaks until the engine has been running for 30-40 minutes, by then, almost done cutting. As I understand it this engine is already past it's normal life expectancy. I bought an identical cub mower for $400 with 250 hours on it, I gave it to my little brother.”