10 bore 3 1/2" & 1-5/8's oz. shot? must have been a steel shot load.
What does the ball weigh that you are going to use?

If less than 711gr. (1-5/8oz), you should be able to put in a 12 bore wad or wads to increase the height of the ball inside the case to get the proper height for a proper crimp.

I take it from your description that the case mouth, folded back inside the hull with the ends of it pointing straight down the inside walls, contacting the ball & holding it there.

When fired, about 1/2" of case mouth must reverse backwards to unfold and you are concerned about pressure increase form this 'extra work'. I would be too. I have a feeling, the ball will squeeze down a bit to ride over case mouth, and the following wad will attempt to reverse the inverted case mouth while it passes. The question is will this rise pressures too much. I don't know, but I do not like that scenario one bit.

Best to take it apart and do it right - get the wad height right and record what wads were necessary to do it.