i dont know if it will fit, but regarding to the lambdas, you plug the first sensor in to the new manifold (the one thats currently in the top of the vtr manifold) an dthe second one you can buy a sleeve, or make one, but GMC motorsport sell them i believe, so you just screw the second sensor which is mounted after the cat on the standard system into the sleeve so its reading clean air, thus stoping your EML from coming on on the dash. or if your not bothered about the EML just unplug it or leave it tied somewhere in the bay. all the second sensor does is tell the car the CAT is working, so it wont do any damage just unpluging it etc.
hope this helps.