91mm has been done, and i think one slightly longer, i remember Oselli did a combination making 1610cc, I think with 73.5mm pistons so that would be just under 92mm...
I wonder how long a stroke could be used before things started hitting the gearbox, if the cam lobes were ground off ?
I've been following this thread and wondering if that one would get a mention. The 1596 was a 91 x 74.7 mm is the biggest I'm aware of, but it was found it had next to no 'advantage' over those around 1500, the limiting item it seemed was the cylinder head and getting enough flow through it.
While different block varieties, it's somewhat amazing that the A Series has covered capacities, in a very large number of individual sizes from 803 cc to 1596 cc.