The used ST 1100 and 1300 bikes sell for a lot more than the Kawasaki Concours so that tells you something. The 2004 Concours I had was a very good reliable bike but extremely top heavy. I hurt my self by dropping it on my foot in an attempt to keep it from going over. After the trauma causing blood clots in my leg, my wife strongly suggested I sell it. It took about a year and I continued to ride it and brush up on my riding skills. At the end I would have kept it but I promised my wife I'd sell it.
Glad you got your money back. If it got lost at the border, that would be a situation where it would be hard to pin the blame on Pinwall. But, they are the retailer and they should make good on the purchase. Cost of doing business.
If you hone it with sandpaper, don't sand perpendicular to the piston. Sand around and around the cylinder. Sanding perpendicular will cause it to not be able to seal.
Around 1990 I was coming out of an auto parts store in Cary, NC and this teenager was headed towards his Maxim with oil he just bought. I stopped and chatted with him. He was 19 and he said he had ridden it to California and back. Said he carried an extra can of gas on the back to make sure he got across the deserts. Rear tire was completely slick. Nice kid. An adventurer!
Sounds peculiar that all valves would be out of spec. Make sure the engine was in the correct position to check them.
Way back my 1975 Honda Civic with the 1488cc CVCC engine had solid lifter valves to be checked. The manual said position the engine in one position and check half of them and another position and check the other half. That didn't work. I finally positioned the engine where each cylinder was at TDC on the compression stroke when I checked each of the 4 cylinders. That way I got the clearances right and they didn't click from having too much clearance when I finished.
The four holes may have been an attempt to prevent the sliders from opening very much and therefore not richening the mixture as much. I'd check the jet sizes to make sure they are the stock size.