Now that is a trickier question as memory module sizes tend to get smaller as process nodes are advanced. What they actually choose to put on a GPU in terms of GDDR5 is going to vary by memory vendor and OEM.
Which is why I have asked for the exact card to be able to give a more specific answer.
VGA memory heatsinks will certainly fit, as the spacing around memory modules is usually about the same on any given card. Those 14mm ones will probably be fine. They don't have to be an exact fit, you will be gluing them on with thermal adhesive.
Simplest method would be to take off the GPU cooler and check, plan out what you want to do, then reassemble it. You'll want to order some thermal compound, not to be confused with thermal adhesive, to reapply the heatsink ahead of time. That would be good practice if you haven't disassembled a GPU before.
Once you have the measurements and a plan, it shouldn't take long to select the parts.