my 5 lb CO2 tank fits on the ledge behind the 2 kegs and it's a clunker as far as 5 lb tanks go so I think you'd have plenty of room there or beside the keg- the only issue I'd be worried about is the pin lock keg will be a tighter fit, as they are a bit (1 inch?) bigger in diameter than ball locks I believe. Because you'll have plenty of side to side space, you wont need to cut the shelf ledges, but i'd think you'd still definitely need to remove the plastic shelving on the door. Like I said, this comes off easily from screws around the perimeter of the rubber gasket, but it might leave too much wiggle room between the gasket so I actually cut around the perimeter of that plastic shelving (leaving it screwing in)... let me know if that doesnt make sense, but you can experiment with the door on your own.
I'd measure/look up the dimensions of your pin lock and see if it will fit front to back- might need to cut out a cardboard circle and see...