JB Weld
I used JB Weld on the last wheel I did.
First , I took a Dremel and V the gracks and splits. Then I reached in with compact soldering iron and fused the cracks together. Then skim coated with the JB Weld. I did leave enough below surface for a thin final coat of plastic filler. Prime and paint satin black or gloss then knock down with 600 and then rubbing compound. Be careful what rattle can paints you mix together as today's re formulated products are not compatible and its easy to have a nice job go wrinkle finish
Plus one on the old wife's tale of the black plastic being Ebony wood. My bet is a guy scored a stock wheel and had to explain it to the MRS when she heard how much, and the white lie was born. "Of course it was that expensive look at the fine Ebony wood detail and crapsmanship."
Most of the good old strippers non water based will eat plastic. So avoid them as well as the heat stripping electric or torch methods.
I would pick a black colored resin next time as I replaced the broken out plastic with wood putty and even colored and stained wood putty will only yield 5' results. I finally ended up masking and painting with a very good quality black enamel then covered with 5 to six coats of good old boat varnish, which improved it to 2' quality.
If that route is chosen the wooden edge does break out on removal. If it does break you will wish you left it alone. It is a very fiddly and PITA to remove broken sections of the plastic . Unless there are big areas already gone, I'd avoid changing plastic.
That wheel I repaired is gone with the MK1a but looked one of the best parts on the 10' car it was affixed too.
I have the old STOA articles to share