Sci guy, if you're still following this thread I wanted to mention that I sympathize with your desire to remove the big Stronglight "pants guard" that's installed in place of the outer ring. They are kind of homely.

It would be very easy to do. All you need to do it unbolt the guard and both chainrings--the small chainring will be set off from the outer one with spacers. Then hang up the pants guard from a nail somewhere and bolt the rings back on, with the big ring in the outer position. You won't need the spacers anymore, and you can re-use the existing double chainring bolts unless they're too rusty or stripped.

Since you'll be removing the original spindle when you service the bottom bracket (or have someone do it for you) it would be no additional effort to replace the original spindle--which is probably a 123mm--with a 118 mm spindle, which is the one you want for the standard double configuration with the big ring in the outer position.

118 spindles are not at all hard to find. Your local bike co-op may have one. They also turn up all the time on ebay--here's one listed now:

VINTAGE Stronglight 118mm Spindle for Bottom Brackets | eBay

If that's too much trouble I think I have a 118 here somewhere, and I'd be happy to trade it to you for the original spindle. The original is the correct size for triple conversions, which is something I do fairly often.