I'd also recommend more than 8GB, it just adds some open space that you'll probably use at some point. My TG renders here never used more than 6GB but 8GB is likely to be a limit one day. Make it 16GB and you're safe, and make sure you have some free slots in case you need to add more.
I have made an interesting experience here with my new PC when compared to the old one. The new CPU has almost the same GHz/core (~2.5 GHz) and more cores, but the newer CPU architecture makes a huge difference. In numbers, my new PC should be around 2.5 times faster than the old one, but its more recent architecture makes it even speedier. So whatever you do, make sure to invest money into a more recent CPU as well.