Oh, don't worry: I don't know what I'm doing. There are some things I can do, and some things I know, but after I accidentally destroyed the electrical system in a K5 Blazer I was trying to do stuff with, I outsource anything that I don't know, and don't feel bad about it.
I had the head done by someone reliable and they had the head decked by someone that builds engines for Stateline. I had all the right parts, even new head bolts. Where as before I saw some coolant weep or leak around the heads, I see none of that. Doesn't mean it's not possible, but I'm not seeing it right now.
After finally getting some chatter from Daihatsu boards, it seems like this tstat comes with the right gasket....that is always stretched out. A smaller gasket (by a millimeter or so) that just fits around it and then, supposedly, it fits right in. That's today's job: finding one of those at Autozone/Advance/Cargo. One of them is bound to have it. If that doesn't work, Napa is on the other side of town...and I could try J-town if need be, too. Hoping to get this guy back on this afternoon and seeing what we can see.