Neil - You mentioned not having gasket sealant or dressing. I've used HYLOMAR Universal BLUE gasket dressing on my last 2 Kohlers, and it's been used on a 302 & 351 Ford, and an IH 7.3L PSD, haven't used any on a FARMALL yet but that day is coming.
If you check Hylomar's website they list the companies that use and recommend Hylomar for sealing gaskets. I used to use Permatex in several different flavors, but I kept having vacuum leaks on 1/10th and 1/5th cubic inch 2-stroke glow plug engines burning alcohol & Nitro-Methane fuel with a few percent different types of oil, including castor bean oil. The Hylomar Blue sealed them up forever, Permatex about 2-3 weekends of racing, they were 1/10 and 1/8th scale RC race cars & trucks. My Kohlers don't leak either.
I used to be able to buy it at Blain's Farm & Fleet when Permatex packaged it for Hylomar, but I have to buy it on-line now. The thin shim gaskets in a Kohler engine, a thin swipe on both sides keeps those gaskets sealing and the die casting will be easy to remove, Hylomar doesn't harden. And the gaskets in the valve spring compartment, same deal, ditto the oil pan.