Wow you are the 2nd person besides me that thinks the L33 would be a sweet swap. My trusty tape measure says the stock engine in my 80' 244 sits 3/4" towards the drivers side at the front of the crank shaft.
For exhaust the truck manifolds are not going to work without butchering the car, take a look a late model Vette manifolds. I am currently looking at the 2000 or so model year sheet-metal manifolds as they look like they really hug the block and they are much easier to modify as they are steel and not cast iron. For the cleanest LS swap ever done on a 240 take a look here. http://forums.turbobricks.com/showthread.php?t=222596
I saw this car a few weeks ago and it is very clean. He said he put the engine in where it fit the best and modified cast iron Vette manifolds worked fine. NO BFH was used in this swap. He did have to add a steering rod heim joint and extend the steering shaft to get around the manifold.
On my swap I will be using the MAST conversion oil pan as it fits with no mods to the cross-member. It's a bit pricey at ~$430 but it solves so many problems and just bolts on - done deal. I will be using a Z-spec T-5 trans in my swap and am very seriously thinking of swapping in a short stroke 4.8 crank and rods into the 5.3 aluminum block to loose the torque that could break the T-5.