Drop spring hanger help

[sleepy350]

Hey guys working on my Dad's 74 today installing drop spring hangers. Got the old hangers out but ran into a snag when installing the new ones. On the hangers my dad got (I believe they're from Western Chassis) the bolt holes don't quite line up. I can get two to line up but with two lined up the other two factory holes are about 1/8" - 1/4" off. Do you guys think this is something that would be safe to just oval out with a file? Factory comes with 4 rivets; if I were to oval out the holes with the new hangars there would be six bolts, two of which would be oval-ed out so I can get them to line up. If it were my truck I would just do it but seeing as it's my Dad's and he plans on driving a lot I just want to make sure it's safe. Pics below:






Thanks in advance!

-Angelo