Welcome to the forums Diamondjax! You should go to the Welcome Wagon thread and introduce yourself you may get a faster response. Oh yeah we all love pictures around here so if you got some post some!....Longroofs Rule!
Most headers for Chevelle, and Novas will fit. Just make sure the tubes clear the ports, or you will have turbulence that will rob you of your HP. You must modify your trans crossmember to accommodate the left side pipe. If you are going to run the pipes all the way to the back, you need some heat shielding along the left side of the fuel tank, and filler hose. You can get the parts from a 94-96, or wrap the pipe in header wrap. A third alternative is to make a sheet metal shield that clamps to the pipe where it descends from above the axle until it passes the end of the tank. You must also relocate your oil pressure sender with a 90 deg. fitting, so that it lies along the side of the engine/trans. You will also require a patch cord for the O2 sensor. I made a patch cord using an old O2 sensor, and a pigtail like the one on the harness wire. I crimped them together because the O2 sensor wire is stainless steel. You can locate the O2 sensor on the collector but only on the top half. Check for clearance. When you install the exhaust put the trans in first gear so you do not have interference with the linkage. You must have 18 inches of pipe beyond the O2 sensor to avoid erroneous signals. If you want side pipes or have them exit in front of the rear wheels, there are mufflers that the intake and out pipe are on the same end. The left pipe will be very close to the floor of the car at the rear seat. I put hangers on the drive shaft loop bolts to stabilize the pipes, because the left side will not have a mount like the one on the right side at the transmission mount. As long as you keep the pipes "one finger" away from the floor, you will not have any problems. If you have the auto level, you must remove it, because that is where the left muffler will go. You may want to look for a 350/5.7L/LO5 before you spend a lot of time fooling with the exhaust. You need the computer from the LO5 for the swap, but everything else will bolt in. The 91s all came with 305/5.0L/LO3s. If you do the exhaust first, it will still bolt in with the oil pressure sender change, and patch cable for the O2 sensor. The rear plug on the passenger's side may be difficult to change with the headers installed.
Nice Fred! I think you presented him with all the details to get him going in the right direction.....Longroofs Rule!
Forgot one thing...You can get an exhaust hanger for the left muffler from another 91-93 car. The one on the right will bolt up to the existing holes on the left.