I don't live in CA (wish I did!), but I'd like to comment if I may. Having been the son of a shop owner, an employee in shops, a manager and now, "just" a customer, I would say this kind of thing should NOT happen at a decent shop. Of course th operative word being "decent" - a manager who talks straight and doesn't over-promise, an understanding by you that the shop makes $$ with insurance work and a willingness to provide before and afters and references as requested. As well you need to know a little before going in.
I think any shop can do the work you're asking for. They don't need to specialize in E-bodies and - if I had my way - I might shy away from smaller "resto" shops. Bigger shops GENERALLY keep promises, have long term employees and stand by their work.
Tell the manager of your past headaches and tell him/her you won't have that again. Get a firm quote to do specific work. Of course it will depend on what's underneath, but a Quarter Panel Replacement for example is (FOR EXAMPLE)14hrs, a drop-off is 4 hours, a complete paint is 12 hours, high-build and block sanding, add 16 hours, sanding and polishing clear coat 8 hours... most is by "the book", give or take a few hours, not 20! If there's extra work required, they are required to call you, show you and discuss your option. Educate yourself with the many sites on the net. Check out Autobodystores.com and ask for the times for the work you want done.
Hope you get what you want this time!