rear of oil pan on slant 6 225

That is correct. The part of the gasket that you see is not sealing anything. The part that seals is inside what we are looking at.

The torque on these is not critical. I would think that 100 is a little low and 200 is a little high (that's like 8 to 16 foot-lbs). Personally I tighten them hand tight with a speeder handle (or a short 1/4-inch dr. ratchet) so that I don't overtighten them. I don't use a torque wrench.

The gaskets on the ends (like the one you are looking at) have a metal ring around the bolt hole to prevent overtightening. If the bolt is tight it is good to go.