Thoughts:
1) the section 1 is very well worn, and hence will be pretty much useless for spares. Hand it in for destruction to you RFD.
2) keep the section 2 as a section 2. It will have been proofed as such and coverting it back to section 1 will require reproof.
3) have a long hard think over how often you actually needed the five or ten shot mag of a section 1. In my experience with a shotgun you don’t often get an opportunity to take multiple targets. Certainly with my semi, 3 shots allows me to miss 3 times very quickly, rather than actually to hit 3 times. If you do really need a new section 1 shotgun they tend to be less expensive 2nd hand than a section 2.
Personally I would use your now free slot for something else unless you really need a section 1 shotgun.