20'' wheel question

[snacks]

i read a lot of people needing to shave down the front hub so the wheel will fit, i have 6 lug disk/drum set up and from what i understand the boss wheels i want do come in a larger center bore style (boss 313) i want to stick with 6 lug and my truck is low 5.5 front 7.5 rear have 27'' tall tires on it now and they fit perfect 215/70/15 and 235/70 /15 not looking to use spacers just want to order some wheels and tires and bolt them on can anyone help,o and what about staggered vs the same tire all around , the shop wanted me to go with a 255/35/20 in a 4 corners not sure if thats what ill like