never had to fix one on the trail but sitting in a parking lot when the coil crapped out. it was very easy 4 screws on top of the cap unplug the connector, pull the coil up and out drop new coil in, insert wires back into the plug. put coil cap back on replace 4 screws. to change an ignition module turn the 4 spring loaded clips remove plug from cap, take cap off leaving all plug wires in place, take 2 screws out of the rotor button, remove rotor button, take 2 screws out of control mod. remove ign mod plugs, assembly reverse of disassembly. takes 10 min to completely tune up a hei. all while hardly leaning over the fender
sorry but an hei is not difficult in the least bit to repair. i take that back it can be a bit of a hassle if you are sitting on the motor of a lifted 79 chevy. but so could anything else