Hey Ron, I have a 68 that I’m having carb problems with too. Bad thing is I’m in my busy season so it will have to wait abit. As far as the exhaust manifold we have a 65 that I put Clifford performance headers on that helped it with power abunch, probably at least 25 HP. We used 3″ pipe for the exhaust system. It’s been recommended to me to put on a Holly 500 CFM 2 barrel with electric choke. As far as the dog house being raised, the 68 is about 4″ tall x 6″ deep x 12″ across. This will totally depend on what kind of air filter assembly you go with. Ours is elbowed across to the left and air filter going down. If you want to go original I have one but highly recommend the Clifford. Where in Arizona did you get one? 68 was from Tubac.