Small world, Morgan, #203 and #204!
Yes, I had to hog out the lower inlet hole, too, and had a lot of fun with a rat-tail file, die grinder and saber saw getting the head to accept the business end of the thermostat. I was toying with the idea of getting a piece of 1/2" steel and machining a spacer but managed to get it to fit. The outlet hole is off center because there's a bulge in the casting for a stud right next door. I turned the water outlet on a lathe to get the relief cuts for the t-stat flange, so that was no problem. Funny the choices of metal they use in these machines. The water outlet was cast iron but machined beautifully. The actual water outlet was the thinnest metal I've ever seen that was threaded, and it was welded tubing. No thank you! The piston wrist pin was also apparently a casting that was machined and then chrome plated, but never cleaned of casting sand! Is a puzzlement!
When you pull the rod bearing cap, note the marks on the side so you can reassemble it the same way, and if you're going to remove the dipper from the lower bearing cap note now many turns you need to go to remove it, too.
Good luck,
Quinn