Personally I'd just run some video benchmarks and if it survives that, I'd go ahead with the SSD install and hope for the best*.
😀 Remember, if it does eventually die, you can always just remove the SSD later and use it for something else.
BTW, my own 2010 27" i7 iMac is working great with no problems, but I only installed a 250 GB SSD in it. It's a secondary machine and I just so happened to have an unused Samsung 850 EVO 250 GB lying around, so that's what I used. Currently it still has 225 GB available out of 250, since my family mainly just uses it for surfing and email.
Come to think of it, if you don't want to invest too much into this machine, you could just get a lower end 240-256 GB SSD like the Crucial BX500 (US$35) or even something like the Lexar NQ100 (US$25). Or if you want more space, the 480 GB models go for $55 and $45 respectively.
These are DRAM-less models, but they would be fine for this purpose. I've not personally used the Lexar, but several people on Amazon.com say it works fine on their older MacBook Pros. However, I have used a Crucial BX500 in my Mac Pro for a while and now I'm using that BX500 in a 2008 MacBook, both with good results. IIRC, I believe
@Amethyst1 also uses this drive in a Mac.
*However, I wouldn't necessarily try to use it for anything super GPU-heavy. The machine is kinda too old for that anyway. As long as it can surf, play YouTube video, and do other mainstream consumer type stuff without freaking out, I'd take that as a garbage dumpster diving win.