You shouldn't have any emissions problems with that set up.
Ages ago, with a not so aggressive set up like now, I went through NJ inspection and passed.
I had an edlebrock cat back, catco high flow cat, headers and other mods.
As for welding..... I go to a local meinekee shop by me.
If you need more info on the shop let me know.
BTW, welcome! I know ya from fbv6