I have used one of these. The fibreglass ones fit quite well and have the original patterned finish. Molded off an excellent original. Just don't spray paint them with too heavy a coat of paint. If you're not going satin black ask for it unpainted so as not to build up another layer of paint. They come as a solid piece with no vent holes although the outline of the holes is there if you have the patience to drill & file!
SFE