I have just did it in the same way and with the same kit. I was not keen to remove the dashboard so I did it directly which is manageable (if not above the cluster). For black dashboard, it is included in the kit. It is also possible to paint with a sponge (in the kit). Not perfect but largely better than the former plastic cover.
Thankful my 85 380SL only had one small short Crack from the defrost vent to the windshield which I filled easily with black moldable putty that dries in minutes. And I used the same putty to fill any little gaps around the outside window sill seals. Barely noticeable
www.furnitureclinic.com I bought it here. Depending on the repair area a starter repair kit should suffice. I would always recommend custom mixed colors unless standard black maybe.
You can use a scrap piece of leather and emboss the final layer- alternatively when already a bit dry use on hot iron on the leather scrap to soften the filler before paint. Hope it helps
