Imo a good solution would be make hp chooseable between physical or special.
70 bp is not that op and all pokes can learn it so the new moves are not required (physical bug, fire special ground, fight etc)
Also this requires effort which is a important point imo since is not like free buff (most ppl gonna need to rebreed and hp is kinda hard to get+money sink) and a lot of pokes get buffed but no get op (115 bp if stab)