Mountain Flying with a '73 Charger?

I have about 800 hours total and 100 hours in a '73 Charger which I will soon bring to the area near Pueblo, CO. The home field will likely have an elevation of 6050' - runway length 4,900'. The engine has recently had a new cylinder and top overhaul. Takeoff will often be near gross. I know the POH says it should be workable unless the density altitude rises too high. Does anyone have real-life experience indicating how I should expect the Charger to perform under these conditions?