Need some advice. cant install this budget boost

So a friend of mine purchased a 2 inch bb lift from rubicon express and yesterday when wr tried to install it we hit a wall when we realised we couldnt get his front bumpstops off to install the spacers since the bolts were so rotted. Has anyone else ran into the same problem? If so, how did you manage to get them off? I need some advice. It wont let me attach the image because its too big but the bolt inside is so corroded that the head is nearly gone