I haven't run autocad since 2012, but, from what I can see not much has changed, in that it looks to be still single core threaded. So adding another cpu wont help except for the occasional render. You'd be better served with a higher clock cpu instead like x5470 or so.
Any ssd will generally improve quality of life in program start up and file transfers/saves.
They say that 8gb is the minimum requirement, but if doing large models 16gb would probably be better.
You won't need a strong gpu as long as you only model in 2d, if you intend to render in 3d, you'll need something with 2gb vram or more.
I think finding a certified gpu would price you out of budget even with an older model. A consumer gpu should work however sometimes there may be crashing or artifacting, I didn't have any problems back in the day, but idk if 2019 is picky.
fast cpu>more ram>gpu>ssd