I do not know my SBF engine generations like I do my Chebbies but the basics are the same. On the production years in this mix the pulley bolt pattern and depth are variables. What about the timing mark location or its balance as these are externally balanced.
I had to look up if there was many options early to late production and found the 3 bolt is a critter different from the 4 bolt all together. Here is a link to Jegs showing 3 or 4 bolt and 28 or 50 OZ. but all the same OD.
http://www.jegs.com/p/JEGS/JEGS-Perf...38152/10002/-1 and
http://www.jegs.com/i/JEGS/555/51660/10002/-1#