Well, I don't think they're scammers.
Anyone redoing stuff that requires plating will likely wait till they have a batch of parts keep the cost down and quality up. Not too many platers are interested in doing "one ofs" and if they do, the quality is usually poor. Turnaround will also depend on whether you want your own part back or a swap from their stock - if they have stock.And it will also depend on the condition of the junk you sent them.
So there are a lot of variables and reasons for long waits. That's what you have to live with for quality work.
I have a friend who ordered a repro chevy air cleaner off ebay. Price was $1500.!! He waited two years but he finally got it. There were times when he thought he'd been ripped of BUT the guy had a good rep. The thing is hand made and is a work of art.
FWIW I think Passion For Mopars has a site that explains their resto process. Its impressive!