Sounds like a solid plan. If you still have original 02 Sensor I would consider replacing it. I think I used oxygensensors.com fast service and a decent price for a denso unit with oem type connector. Also did you clean the EGR port in the intake that runs in the plenumn from the Pipe to the valve? Mine was full of carbon. In my opininon if you get it running right you should be able to get it to pass without replacing the cat..

99 Gen 2.5, fixing blown head gasket
89 SWB- 33's, ARB Front locker, SR rear locker/axle, SR F brakes, winch, WST Offroad Armor all Around, 2.85 Aussie T-case Gears (SOLD)
Sold: (2) 95 SR's, 86 SWB, 90LWB, 91 LWB
-Can Change a timing belt in my sleep..