I have to agree with David and Rick. Both the plugs and the elevation will cause serious changes to the setup of the car. On the setting on the float you really can't say what is normal..well you can but whats normal for every car and not everyone will touch the tang in the same place...as well you have to remember that on a 289 vs a 427 the carbs are angled at 10deg and that means that the fuel will overflow at a higher setting...we had a car this weekend that because of the vibration and the floats it was spewing fuel out the pump jet..this was causing the car to load up at the stop lights and then when he took off from about 1500-2000 it jumped and stumbled like mad...adjusted the floats WAY UP and no more problem...now thats not recommended if you are going to be racing but hell he can drive a mile after turnin off his fuel pump before the carbs run out of gas....trust me he knows
The elevation will cause problems because obviously you are moving a different density of air...if you had this engine built at a higher elevation than you buy a significant amount then you are going to have to jet it way back down..
Matt