I have a Holley Truck Avenger carb on a Chevy 350 with a mild cam and HEI. I have recently moved to 4200 feet in elevation and need to rejet as my rig is running super rich. Here is my dilemna/question. If I spent all of my time at 4200 feet the rejet would be pretty straightforward as Holley recommends jetting down one size for every 2000 feet in elevation. The problem is that most of the wheeling I do is at 6000-9500 feet and I need to drive to the trail which can involve highway time at sea level. Any recommendations on where to start? Main jets on the Truck Avenger are 68 and secondary jets are 89. For what it's worth, the motor runs slightly rich at sea level with the stock jetting. If I jet for say, 6000 feet as a compromise will I do damage to my motor at sea level? Lastly, will I need to make any other adjustments aside from jets and possibly the idle mixture? Sorry, but carb tuning is new to me and fuel injections isn't in the budget. . . Thanks!