Also, the Holley manual has this info:

Installation Notes
The programmable timing feature of this system is available either by: 1. Using one of the following distributors: 1980–1/2 through 1990 GM 7–pin (coil–in–cap); 1984–96 GM (external coil); 1984 – later Ford 7–wire TFI. Use wiring harness adapter P/N 534–47 for GM istributors and P/N 534–48 for the Ford distributor.