I agree with HRL. Just look for ignition parts for any 1971 GMC big block and compare to yours. The only thing that is specific to the "tall deck" big blocks is the length of the distributor drive. The very early TD BBC also had gear drive cams. Other than that, I believe GM used a lot of common V8 ignition parts from the 50's throughout the 70's. Try RockAuto for a 1971 GMC 454 and take a look at the pictures.
SimS
