1080p is 1080p, whether the screen is 23" (recommended) or 60" the demand on the GFX card is the same. Any the 144 Hz doesn't change things all that much. I have (6) 144 Hz or better screens here. The 760 will be a bit stretched in modern games, but a 1060 3GB is more than enough for games at 1080p. If ya have any doubts read the review here:
https://www.techpowerup.com/reviews/MSI/GTX_1060_Gaming_X_3_GB/6.html
That card overclocks 14.5% (see page 29) and with that, you'll get over 60 fps in 14 outta the 18 games in the test suite with the remaining above 40 fps. And no, 6GB version doesn't add much of anything. The 6GB version of the card has 10% more shaders so it does have a speed advantage. But the shaders are what poroivides that atvantage, not the extra VRAm. This is made abundently clear when ya look at the performanc summery where at 1080p the 6GB w/ the extra shaders has a 6% performanc advantage. And looking at 1440p, we see that that advantage does not change which would be a given if VRAM was in any way coming into play. Moving up to the 6GB version can add $200, which will be real hard to justify for 6% more fps.
This misconception that games run out of VRAM when they don't occurs because there is no utility, the venerable GPUz included, that actually measures VRAM in use. It's like when a credit agency does a credit check... when they see your Master Card account, where you have $500 charged on your $5,000 credit limit, the credit agency reports $5,000. But in most games, you are going to be 60-80 fps, not really enough to allow full benefit of 144 Hz technology where you can use Motion Blur Reduction.
Now a 960 will give you about 62% of the perfomance of the 1060 3Gb ... the 760 will give ya about 91% of that. So id the 1060 3B gives ya 56.9 fps at stock, you are looking at about 38.8 fps with the 760.
However, unless you plan on sitting on a couch 10 feet away I would strongly advise not getting a 31,5" monitor @ 1080p. The PPI (pixels per inch) on that monitor is less than 70 which will provide a very gariny image at noremal viewing distances. Anything ;less than 96 ppi is not recommended and these days, < 100 ppi is rare. A typical 1440p 27" monitor is about 108 ppi.