Got some nice things happening there with your chiseled stroke technique. Personally, I would keep your technique happening and make sure that your drawing is accurate, or at least adjust along the way. What often happens is that we fixate on solving one visual problem, as with the painting technique, and ignore another one, as with the structure of the object one is painting. In this case that lower lip, with no context other than itself (and perhaps the Rocky Horror opening), one can only look at it and compare it to normal anatomy. The overall shape is a bit off, but it can be fixed if you have a clear reference photo. Were I doing it, I would put the original on a layer and reduce the transparency to see how the shapes differ and go in and clean it up.
But the paint technique is your own and you can really experiment with making it work in infinite contexts. If you have a chance, I would recommend looking at John Berkey, the illustrator, who took this kind of technique to a masterful level. His forte was machinery and spaceships and hardware. But that was just who would hire him -- sci-fi book publishers and so forth. And that was his niche. But he did lots of other things as well, but that was what he was known for I think.
"Not a bit is wasted and the best is yet to come. . ." -- remembered from a dream