Only 1 person can log PIC time, the other pilot/passenger can only watch and put nothing in thier logbook......
I am an instructor and even on a 2 year check flight I cant log PIC unless the pilot I am assessing and I agree how the time will be logged, ie I am giving him some instruction.
You and your friend could do 300 hrs together and agree how you will log it. Each doing 150 hrs each PIC. the other 150 is just air time and counts for nothing in terms of logbook.
Also good luck if you think you can be a good instructor after JUST 150 hrs experience......