Get 78+ combat and you will be perfectly fine, you have just over 3 weeks to train so grind hard. The aim is to have 90% of the clan above 80 combat by next month so we are prepared for preps.
THIS DOESN'T MEAN GAIN DEFENSE FOR COMBAT LEVELS I HIGHLY RECOMMEND YOU TO STAY 1 DEFENSE UNLESS YOU ALREADY HAVE DEF BEFORE THE LPC MOVE.
This is because the combat cap for preps is going to be 88 combat so if you're any higher than that you will be sat.
I don't want to see level 60's or even low 70's at the trip as you will basically be useless as the combat bracket is very tight at the moment if you're a significantly lower level you will get sniped / hit by smaller lower level teams or clans and we won't be able to help you at all.
I know this from experience as I'm in an lpc myself currently and the most dominant clans have close levels which can be very beneficial fighting at low / mid level wilderness as this is where most of the action will take place in f2p mostly.