Outer rocker panel replacement issue

[70sangersean]

So I'm replacing my outer pass. side rocker and the issue I am having is when I line up the rocker edge with the door edge in the front, so its flush, I end up with a big gap between side of the front pillar and the rocker where it needs to be plug welded. I have my door aligned about as good as you can get with these trucks. If I push the front of the door in anymore it will not be flush with the cowl. I,ve tried two different rocker, one fitting in there better than the other, but both have the same issue. I didn't pay attention to how the original fit, but it had at least a half inch of bondo in it so it probably didnt matter. I know the truck was wrecked in the right front, but retained its original panels (with a fair amount of bondo). The floor, inner rocker, pillar and firewall don't have any visual signs of damage. I've read a lot of threads, and I know I can expect there will be some slicing and tweaking to get them to fit just right. But I haven't read anybody having the issue I have. An 1/8" gap wouldn't concern me but a 3/8" gap doesn't seem right. Any input would be greatly appreciated.
Thanks, Sean