Re: wood floor over concrete
We did a below-grade engineered (tigerwood) floor in BR-111. It was glued down. I hope never to have to go through that ordeal again.
Engineered, or BR-111 at least, requires that the slab be level to 1/8" within 6 feet. That made us use a whole lot of SLC. Then, the floor had to be sealed with a proprietary polyurethane sealant, and only then could we glue down the floor.
There's a floor guy I'm acquainted with who claims that sealing+ 3/4" plywood glued and nailed down, then any hardwood can be installed.
Remove not the ancient landmark, which your fathers have set.