Making my own exhaust?

Hello, I own a 92 le-5 b2200. I recently dropped my cat out because they were plugged and overheating my engine. Now I just need a flange that can fit on the stock headers. I don't have access to many tools but I do have a welder. Please help!

Pound out the stuff from the inside of the converter with a large pipe and hammer, use that as an open pipe. Then stock gaskets will fit.

That would work but in the process of removing the old cat, the bolt closest to the block snapped :/

Muffler shop