Hello Tom,
Your question sounds so familar to me.
Beautiful leather you have got - if it wasn't cracked.
Your interior color is not parchment but something else. White grey or light grey or so. There were about 23 different leather colors available for the 230 SL in the old days, e.g. among those at least four red shades.
What does your data card say in field/box no. "17 Ausstattung" (= interior trim code)? 207, 209, 219 or 221 or what else?
See also here:
https://www.sl113.org/wiki/DataCard/UpholsteryCodesBasically,
your interior
can be rescued but it will be a long and tough story.
Basically you need to replace all broken parts (the outer bottoms of the seats or the inner perforated pipes on the other seat) with "as close as possible" "donor" leather you can find.
That "could" be either new one or parts from interiors of donor cars; i.e. old W108 or W111 interiors.
Colors could be slightly different from the donor interiors but should be "lighter" since it is very hard to redye leather from a darker to a lighter color.
There is a lot of effort, finding for the suitable donor parts, etc. and especially a strong will of your own necessary to go this route - which I think is worth it.
Old classic leather looks best in our cars; I personally find (brand) new leather with too coarse surfaces, flat shine and wrong (only standard available) colors ugly in our cars.
However, be aware that most interior shops are not keen doing this kind of job.
Most refuse that task or only want "to sell" you everything "brand new" because that is the much easier way for them, provides the best (most perfect looking) result and will not provide them with "bad experiences" of cracking old leather during the re-sewing process.
So..., it's all up to you.
This is what original leather can look like (not mine) - only carefully re-done.
Good luck, go that route & keep us updated !
Best,
Achim