I only can say … try it!
I have not a PiTFT 3.5’ here, so i can check if it fit the holes, but looking at the specs, it seems that the difference is less than 1 mm. I you use slim bolts, you should have enough room to fit it. I can include 2 different bolt sets so you can choose what fits better. Probably the display window wont fit perfectly, but there is some margin, so could be OK.
Anyway, if finally you don’t like the result, you can buy a PiScreen. It’s a good display