The only thing I can say, is make yourself happy. I wouldn't personally care what anyone else says if I'm happy with it.
I have only attempted a couple of engines and that's it. When something personally bothered me, I had to fix it to make myself satisfied. Some things are harder to accomplish. Some things I needed help on from others.
A grill on top of the MP15AC hood was an example. I attempted to scratch build it from brass wire. That was too complex to make perfect. Although I would have been proud to get it right, I had to do what I could to make a reasonable copy.
