What's the fastest way with gold to level boost 1-80 now?

I checked the old DF spots and the mobs were level 70 and confirmed a level 80 gets no exp there. Not sure about 1-70 here tho?

I also noticed my level 20 paladin twink can't pull the map in TBC dungeons now due to scaling but i was still curious would a partied member still get EXP with a exp locked char nowadays as I think lv11 warrior twinks are still fast?

Lastly, I was wondering if a level 81 + dungeons was the play as I had a level 81 healing priest 1 shotting bosses somehow in a wrath dungeon.