You would not be having the problem if you were just had a little more patience. You just can't assume things. Look here it is taking me up to four months to get some parts lately. Matter of fact I am currently awaiting a muffler that should be available the first week of December; hopefully.
I was once was told assume was acronym for making an (ass) out of (u) and (me). Experience is a great teacher but can be expensive at times. Hopefully you didn't clog any of the internal oil passages but you find out if engine fails and you have to have a replacement. RTV will setup in 30 in the open air but will take multiple hours in a confined space.
As for parts you just can't order any odd part and expect to work; you must order and receive the correct PN. You do need however use a reliable vendor such as Partstree or Jack's. eBay and Amazon are not good sources most times. But they will only send you what you order, they are not mind readers. In my case I do have a good Kawasaki distributor I use here but I am a regular shop.
What do you mean hard to find info?
Service manual and IPLs are available online. Just got to ask for the links.
IPLs for the engine is available at
https://kawasakienginesusa.com/
They are also available from
https://www.kawasaki-engines.eu/en/support/electronic-parts-catalogue/ Although that site does have a different PN for the crankcase sump gasket which why I going to be ordering both PNs and compare them. It will take some time as one is not in stock at the distributor I use. I got hunch that they are the same.
Service Manual is available from
https://mymowerparts.com/pdf/