Floor Settlement between Slab on Grade & Crawlspace

We are remodeling a 1950's daylight basement with half the basement foundation a slab on grade and the other half a 3ft crawlspace. There's a gap of about 1-inch of settlement and a 1/2" gap where the SOG and joist framing meet, creating a step in the floor surface.

We have stripped the floor of the layers of vinyl tiles and carpet and now need to "mind the gap" before installing a new underlayment and engineered floor.

My plan was to feather the transition using stacked 1/4" lauan plywood and smooth out those edges using something DAP Flexible Floor Patch and Leveler. The transition "ramp" zone will be about 4 feet wide.

Does all this sound right? Anything I'm missing?

Thanks