Thank you, gentlemen,h

Mine is an Ideal.
The screws were in the proper place as the side lock screw's face is flush and the end has a cross pattern. Its patina matches the side plate.

The rear tang screw does not fit flush in the side plate and has a blued finish on its head.

They are very close to the same length and thread.

With the 0.030 shim under the trigger plate at the rear screw, the rear screw end is 0.035 lower than the receiver tang face.

The right sear measures 0.105" thick and the left 0.081". So, to not use a shim and grind down the left sear, it would be about 0.061" thick. However, I would only grind a little at a time. Or I can add a thinner shim and not grind off so much from the shim.
Do any of these option sound viable? I'll try to attach a picture of the sears side by side.