I don't know the dosage, but I took two getafix blotters in 1994, and they were stronger than double dropped purple oms, or quad dropped shields.
The getafix's were rumoured to be 200ug ish. So, maybe I took 400ug, but I was fully immersed in another world for a good 2 hours, that was the closest I've eve come to total "ego-loss", was at a party in a machine tool factory in Birmingham, people were still trippping, like fully tripping until about 8am...I've never had an experience like it before or since.
I wouldn't knowingly take 400mics again now.
just found an image of them :D