measured floor to flange both sides the same.
front of frame to flange-same,
outer edge of frame to flange-same.
both side pipes level and parallel to frame and floor. Gap at rear of driver side flange.
Assuming that the reatangular side should be placed on the frame and the "ears" ar ewhere the control arms mount.
This would place the left and right control arms in different planes and not parallel to each other.
The rectangular side has a interference with the shock tower and the mounting holes do not align and not adjustment is possible.
Notching a Weiand Stealth manifold like Edelbrock Air-Gap
My "home made" Bridgeport Mill...well, have a milling bit anyway...took a while to figure out how to feed the work so the bit wouldn't chatter. First pass the bottom was uneven. Second pass rigged up a better support and got the notch parallel to the carb pad.