I don't know what you mean by window, but if the timing mark is in the normal location, that should be correct. But the cam can still be out of phase. rereading your first post, a second carb is still doing the same thing. The odds of it being a carb issue with two having the same problem is slim. You said it does run, I bet the cam is off a tooth. I believe a vaccum gauge will show a very weak signal. Typically whan any inprovments in breathing are made, headers, intake etc. the carb needs to be richened a increment or two. But it still will run fine, the plugs will show a lean condition. With all the old carbs I've ever worked on, turning the mixture screws in leans it out, which is the opposite of what you have. It is very easy to misalign dots on the timing gears, you may want to recheck that. It's a cheap fix, but can be a little time consuming. If anybody has any other thoughts, I'd love to read them. It's been several years since my troubling shooting days. I hope this helps, good luck!