Garry, your 280SL should take the part numbers I posted, but the 230SLs ares a different matter. I'm sorry for not considering the earlier models; Naj is quite right, I'm sure. See somewhere on Jones's website the notation that antiques and/or classics can often be fitted, consultation offered. Contact him by the several methods also listed on the site. Of course, I'm spoiled and just pick up the phone, which has worked well with Porterfield. They are a solid, old-line outfit, and if their first-tier phone people can't cope, the next tier surely can. [I think "Nancy" cut through the fog for me once; it's not that she's encyclopedic about the old-timers so much as a capable honcho.] And, back to Jerry Jones: he obviously has an established line to Porterfield's experts. The scales on which these two businesses operate appear to be very different, but they're both likely to get requests for the unusual, from competition to collectibles.
Jim Villers broke this ground a few years back. I don't foresee big problems with correct fitment but if diffugalties do arise, he may have been there afore, at least with Porterfield. I believe they'll make most anything, especially with the frame cores provided, but that our applications are not that exotic, possibly requiring a little conversation at most - - for standard part numbers that just may not be listed 'out front' these days, yes?
Denny