I sell the best mount I know of for a 2wd. I've used them in '73-'87 models, and would love to see how they work in the '60-'72 models.
They align straight up, which moves the transmission forward a couple of inches. With my 4L80e, the mount stud landed in the stock location. My trans cross-member was all the way to the rear. The 5.3 is so much lighter, the fwd position is no issue. My mounts use the OE clamshell assemblies from a late '80s truck. I believe they'll work with your pancake mounts. If you care to try a set, I'll send them out. You can keep the low mount A/C this way. It adds cost to the driveshaft, but saves you the cost of an A/C bracket, and since a driveshaft upgrade is in order, it makes good sense.
I suggest you use Hooker cast iron manifolds. They have the best clearance. Also, get a 2010 Camaro water pump. The lower water neck points lower, and the top water neck is on the driver's side. It requires an inexpensive idler relocation bracket from Dirty Dingo. It will let you use really clean, inexpensive, radiator hoses.
I use a driver side battery tray to clean up and centralize electrical, and free up a path to the passenger side for an air pipe without the space conflict with the alternator and top hose.
I will shortly offer a fan shroud for square bodies. I expect a similar install will work for you. It mounts two 12" GM fans. I'll also have an ecm mount coming soon. Check out my shop page to see how it all fits in my Square. You can message me there.
Tejas Steelworks