I agree with the suggestion to use wider radius curves rather than cutting up O31's and inserting full or short pieces of straight track.
I tried the curve, straight, curve thing on Warrenville many years ago, and was never happy with the result and re-re-did it again using wider radius curves of O42, O54 and (very hard to find in the O27 gauge that I use) O72.
As to re-bending, I've done this, making O44, for example, out of O42, to fit a need. Mark the radius needed on a piece of cardboard (or whatever), remove the ties, and massage the rails between your fingers and thumbs until they match the drawn radius. Replace the ties, trim the ends and you are done. I've done this with the thinner gauge of O27 gauge track, the steel on O gauge may not be a pliable.