Well, you have your old DVD drive to get the form factor from there all pretty much the same you'll just need to adapt your cover to fit.
If you have 8 GB of Ram now you probably have 2X 4 GB under your keyboard and two empty slots in the same open bay when you removed the hatch door to replace your hard drive Use something like
Hwinfo64 it will show you the Timings and voltages and even the brand name of the currently installed ram just match up the timings and voltages and install them in the empty slots. There are a ton of Videos on Youtube on these notebooks.
G752VY-DH72 Win 10 Pro
512 GB M.2 Samsung 960 Pro
1 TB Samsung 850 pro 2.5 format
980m GTX 4 GB
32GB DDR 4 Standard RAM
Z97 PRO WiFi I7 4790K
Windows 10 Pro
Z97 -A
Windows 10 Pro