Are you sure with the perforated soffit there isn't venting?
Have you been up on a ladder w/flashlight & checked?
I need to check better, but I did check one area and was able to feel that there is plywood or some other hard surface blocking the soffit material. The way my overhangs are built I don't have good access to them from the attic as I can't stick my head in enough to see, there is about 1-2 inches gap between the top and the corner of the ceiling/wall, then the overhang is lower then the ceiling. I put my arm in with a hammer hoping I would feel the hammer just bounce off the soffit, but it hit a hard wood surface that seemed flat like plywood as I moved the hammer around.
Now what I am hoping is that there are at least some areas where there are vents. So maybe I'm safe, but I'm probably better off just opening it up from outside and cutting I guess. This is an old house so I'm guessing at some point it looked like this and they just added the metal soffit material over.