Hey, as you can see in that post, as many others, I’m doing well with CPUs even older than yours.
So, with your hardware and the i7-3370 I think you can for sure plot 3 in parallel and maybe 4… (on my NUC I have 1TB drive and I have been plotting 4 in parallel for about 3 weeks in a row without problem).
If I were you I will start plotting 3 in parallel, staggering by 1h each plot, just a few days to see how it goes… and then, once you make sure everything is working fine, you can try plotting 4, but staggering them by 1.75h-2h; it depends on the times you get.
Btw which OS are you running? I really recommend you Ubuntu Server if you are using this machine just for plotting.
PS. I suppose that you have another drive for OS, right?