A 2" BL would make it a lot easier, however if you don't want the BL, you could lift passenger's side of the body up off of the frame so you can work through the wheel well. The driver's side is easier to access so you shouldn't have to lift it. Without a BL you should hammer back the firewall about an .5-1" on the passenger's side for clearance

Even with a BL, I would recommend removing the intake manifold so you can get at the top of teh header bolts easier. Removing teh intake manifold should allo you enough to room to be able to pass the passenger side header down from above, and will also help with th removal of teh old manifold and x-over pipe. You may also want to consider using studs instead of bolts. I haven't had a problem with the bolts comming loose yet, but others have.

I would have flangers welded onto the headers or the ball/socket type connectors for ease of removal down the road.