Rusted B Pillar Cutting?

[Dodgefran]

I would like to ask all of you what cut off tool (electric, I don't have access to a big compressor for air tools) can I use to fit in this small area to cut the inside two sides of my B pillar. I plan on rebuilding this by patching on the inside two sides. The rest has strong metal left to weld to. I plan to cut about 4" up. My problem is, 1. I don't have experience, and 2. my 4" cutoff wheel may be too big. I definitely need help, and am open to suggestions. Thanks ahead of time.


dOOR B PILLAR 2 1938.jpg