Hello, I know it's been a while, but I'll leave this information in case it helps someone. I also had the same problem as the scan lines were overlapping. What I did was modify the ini file called vertical.ini
add these lines
#
# CORE RENDER OPTIONS
#
keepaspect 0
unevenstretch 0
unevenstretchx 0
unevenstretchy 1
autostretchxy 0
intoverscan 0
intscalex 4 <-- is for 1080p
intscaley 4 <-- is for 1080p
what this configuration does is keep the aspect ratio of a horizontal monitor flipped to vertical, this allows the scan lines to be displayed correctly and not overlap, of course the games look a little more stretched than their original proportion set mame, but I remember that in the arcades the technician rotated the monitor of a horizontal arcade and left it as vertical for ship games, it's the same thing that this jsjs configuration does.
Excuse my lousy English since I used a translator