Hi,this is just a shot in the dark so please don't take it as gospel but in the late 80's /90's the 711m blocks and the thick wall wall AX blocks tended to run Kent 234 cams as stock sprint/super sprint cams from the factory as far as I can remember..... It's been a long ,long time, over twenty five years since I left the fold but I'm fairly confident that's correct...ish One person I do know who is an absolute legend when it comes to xf lumps is Roger King who in my racing days built by far the best xf race engines by a mile. I have seen him post/ comment in the forums so I would really recommend spending some time searching Roger out as I truly believe he will have the definitive answer. please post or let me know your results as I'm sure your answer is here good luck Ralph