The engine crossmember has to come off. Good luck with that. Don't bust either of the bolts off. Use heat on the bolts if you have to (and a lot of it) rather than a cheater bar (learned that one the hard way.)
You should be able to get the pan off by bringing it forward over the top of the steering. It's REALLY tight though. I've done this twice and it was a major PIA both times.
If your old oil pan is still functioning...consider waiting to do this until the engine is out of the car. It is SO much easier.
I just did this on my '66 C code 289 THREE TIMES! :: For sure the cross brace has to come out and those bolts can be in there pretty good. I shot them with PB blaster and used a 2ft. breaker to bust them loose.
I have manual steering, so it may be different if you have power, but the center link definitely got in the way from removing the pan completely. I actually took the center link free from the steering box and it would drop down enough to clear the pan.
It is probably the most dirty grungy job I have done in a long time.
Did this with my 69 when I went to a chrome pan. The cross bar does have to come off - my bolts broke free with a cheater bar and a lot of teflon lube before trying to move them. I do have to admit, my car has led a pretty pampered life so rust and corrosion on the bolts wasn't a big issue. I have power steering and that was no prob. The engine was raised slightly off the mounts to get the pan more room to come out and down, mainly not to scratch the chrome one going back on. While I was at it, I replaced the oil pump, screen, and put in a new oil pump rod. Since the engine mounts were loose anyway, I replaced those too - they were the originals. Not that big of a job, really. Just take your time. Oh, yeah, if you replace the pump, be sure and prime it with vaseline or something like that to make sure it gets oil right away.
On a 65/66, all you have to do is remove the crossbar and remove the idler arm bracket bolts from the frame rail. You can then maneuver the steering linkage out of the way to slip the pan out (moving the pan towards the front of the car).
I just did this a while ago, once you get that crossbar off, you can unbolt the steering linkage from the idler arm, then turn each tire out which will drop the linkage enough for the pan to clear. It really is easy, it's even easier if you have an air ratchet to remove all those pan bolts though. ::