PS - you put the screw heads on the metal side, with washers? don't the nuts interfere with the barrels and keys?
This is what the top of the barrel plate looks like with one of my Rivet Replacements, you can see that the length of the screw is just enough to come through the plastic and stop flush with the top of the plastic. Unless you look closely you can't even tell it has been done from the top.
The biggest reason I decided to go this was was because of some of the pictures from other bolt-mods showing mis-alligned bolts, and nuts on top that interfered with key travel or the stabilizer wires (especially right here on the num-pad area)
This is why I refer to the conversions as 'Rivet Replacements' since I am not technically using bolts and nuts. On the bottom side; the size of the rivet is very closely matched by the small washer, this way it also won't interfere with clearance on the bottom of the case.
If you have ever noticed, on the plastic bottom case, you can see small depressions for the original rivet-heads. The flush screws and washers fit in these depressions like they were made for them.
And for the DIY minded people out there; I will be making a kit available with screws, washers, a properly sized drill-bit and possibly a nut driver.