My QT had a cracked case and bad cones, so I was not able to keep it.
I ended up using an Atlas. I know this may be more expensive than some want to spend, but I have been really happy with how everything turned out.
I am using the Novak weld in engine mounts to install a 5.3 L33 and 4L60E. The reference point for me was to use the shared bolt that mounts the shock absorber tower and factory engine mount. I put this through the upper front bolt hole on the new engine mount. With this placement, it left about 1" clearance at the front for the engine/radiator fan, about 1" spacing around the transmission/body, and about 3/4" for the transfer case/body. I did have to remove the heat shield above the transfer case to get this much room.
The Atlas is a lot shorter, and will clear the factory gas tank even though it is a center output. I was able to keep the existing crossmember and use an easily use an adjustable mount from Summit. The transmission shifter alignment looks like I'll be able to use the existing shifter linkage.
One thing I had to do was shift the engine and transmission 1.25" toward the driver's side. I haven't installed the new front driveshaft, but it looks like there won't be any clearance issues at this point.
I really like how the transfer case is above the cross member and tucks in tightly.