Jeep Strokers

I have a freshly rebuilt 4.6 L stroker that I will be ready to start up soon. One of my issues at this point is the exhaust. I'm running a header, Which needs to be custom adapted to my current exhaust system. It doesn't look like it's something I can pull off in the yard, because it has a couple of bends to it. Problem is, I don't have any way to get this to the exhaust shop to have this done. Without the exhaust, and this pipe, I will have nowhere to plant the O2 sensor for my OBD1 system

My question is, would it be safe for my engine to start it up without hooking up the oxygen sensor?

I wouldn't. I'd get some of that cheap bendable pipe rig something up and use that until you can get an exhaust put on.