Gibs you think that the cause is the accelerator, but it isn't. It's the mobo that has a bad timing.
Read Ian's web: http://www.ianstedman.co.uk/Amiga/amiga_hacks/A1200_Mobo_fix/a1200_mobo_fix.html
"If we remove the 22pF capacitor, either by removing it or the resistor, the capacitive load drops from 37pF to 15pF. The rise/fall time is thus:
T = 2.2 x 150 x 13E-12
Accelerator cards with logic buffers have a 3-7ns propagation delay added on. This helps to explain why some accelerator cards work better than others. I would need to re-read the A1200 CPU slot design notes to explain this further.
Your Blizzard is "avoiding" the necessary Timing fix. Perhaps changing your 060 you changed your "propagation delay" from 4 to 7ns or something enough to have it right. As you may know, with other accelerator or without it you'll have the same problem.