Well, I recently put some Pace elastomers from some RC-35AB's (ie 2 big/1 small elastomers in each side) into a set of Shocktech forks (which are basically a UK copy of the Manitou 1 design).
In my case they seemed to fit ok, they were firm elastomers that were bought new about a year ago, so in good condition.
I actually mixed them up with the remaining useable elastomers from the Shocktech forks.
Initially they felt a bit soft, but "ok", to be expected I guess as I'd mixed "Firm" elastomers with "unknown" ones. However on the second ride on them last weekend they seemed to have gotten softer, to the point that the fork crown repeatedly bottomed out on the front tyre tread :shock:
Not quite sure what's going on there :? I'll need to pull them apart and check. It may just be a case of the elastomers settling after a few rides, it could be that I didn't use enough/right length of elastomer in the first place, or it may be that the Shocktech fork legs are wider internally than the Pace ones, allowing the elastomers to compress and also squish outwards.
Either way, they will fit, and work, they just require a bit of trial and error fettling imo.
I tried this option for the same reasons you mentioned, it was either use the elastomers that I had lying around the man-cave, or stump up the readies to get some Manitou replacement elastomers shipped over from the USA, and
I'm a Yorkshireman living in Scotland, so doubly tight with my money