Steering conecting to Pitman arm????

OK so I'm workin on my WJ knuckles and high steer I've got Heims, tube inserts and DOM but just wanding if I can drill out the hole in my pitman arm to 5/8, so I can use high misalignment spacers and heim on that end aswell or do I need to use a tierod end?

You can drill it out. It's been done many times. Of course, use a grade 8 or grade 9 bolt and torque it to spec, like 200 ft lbs.