Leveling compound, wooden floor, gripper rods

I've got an old timber floor, that could do with a bit of leveling out prior to a carpet being fitted (gap visible under skirting in one corner). My concern is if I put leveling compound on it, are the nails in the gripper rod likely to crack it and cause it to break up, or does it have enough flexability in it that the nail will just go through neatly and secure into the board below.

Its an old floor approx 120 years old... its structurally sound, however I guess they did things by eye then rather than use the level

Yeah.. many old floors (and walls are not straight).

as for leveling compound.. I have never heard of it being used this way. So i really don't know how to comment.

Usually people would either add plywood boards down. that way you can still nail into it with carpt grippers.

I means however, that you floor will be a few mm higher than usual. so it can stoop doors from opening properly.

Carpet gripper nails are about half an inch (i think) so leveling it by 2-3mm would be ok.. but personally i don't recomend using self leveling compond as I have never seen it done that way.

You need a fibre reinforced smoothing compound like level flex

Overboard with hard board [prevent boards showing thru]and refit skirting to remove large gaps.
Gripper rod is glued down [hot glue gun] where there is leveling compound or hard surface.