New construction recessed can lights

I am in the process of doing LED retrofit to a bunch of old 6" recessed lights.

After removing the old AT baffle & trim I see two issues.

The eight recessed lights, four under the left soffit and four on the right. They are new construction cans with the metal frames attached to the framing. The left soffit looks fine, where the holes were cut and the cans lowered to be flushed with the bottom of the sheetrock. However, the four on the right the holes are slightly smaller then the cans so the cans sit above the sheetrock. How important is it to enlarge the holes now (by about 1/8") so that the cans (these cans do not have lips around the bottom) can be lowered to be flush with the ceiling? Or no big difference?

In addition, these old cans do not have the "ears" on the inside where you can attach the trims with legs on springs. These trims use two friction clips that claw onto the side of the can and when you push up the clip flips up to secure. Most of the retrofit LED lights use the springing legs. Is there some sort of adapter thingie that will add those ears to older style cans?