71 Dodge Dart AMD rocker install

I had do drill a few of the welds on the a pillar and the door pillar from the inside. There is also a few in the a pillar and were the front seat belt attaches that can only be drilled or seen from the inside of the the rocker once the bottom is cut out of it. I honestly don't even know how they were welded. I replaced the entire wheel tubs with aftermarket tubs already. I can fit a 30" or 32" tire in the back of the car. I have plans of back halving the car later down the road so all ill have to do is extend my existing tubs.