I've just wrapped up the hard part of this swap on my truck. Except I swapped into a 1/2, so some things may be different. Is your Burb or the donor 4wd? Or both? Or neither? That will matter on a few things.
Obvious things are the harness and PCM, the 350 harness will not work on the 454 due to different injector harnesses and sensors in different locations.
Exhaust, you may be able to get the 350 exhaust to fit since it is a dual system and the pipes are somewhat moveable (though it is difficult), but I highly recommend putting the BB exhaust on. Or if you can find a good exhaust shop, just get one custom done. I got 2.5" custom bent header-back for $240, and I took him the muffler (dual in-dual out)
Motor mounts are the same, the BB will slide right into the 350 frame mounts, the only difference is that the BB has frame "stands" and some SBs don't, being a 3/4, yours probably does. The BB will fit into a truck with our without frame stands. Yes, the oil pan will still be above the crossmember, so no risk of hitting it.
The transmission crossmember will need to be moved back, and you will have to use the driveshaft from the BB.
Throttle cable and cruise control box, the cables are shorter on a BB
Intake box and tube
Cooling system, unless your 350 has the HD system already with a 2 1/8" radiator and built-in oil cooler
I'm sure I'm forgetting a few things, I'll repost if I think of them
Things to do while you have the 454 out -
Injectors. Even if they seem good, the factory ones leak down and cause hard starting over time. Bosch and GM both have "upgrade" injectors. I used LS1 24lb, but you would have to have a PCM tune for those. There are 19lb (factory) and 21lb ones that do not require a tune (though a BB tune would do wonders, and it's only $200 for a lifetime tune)
Fuel pressure regulator. It's cheap and hard to get to while in the truck, do it while it's easy to get to.
Oil pan gasket, rear main seal
Spark plugs
Exhaust manifold gaskets
Frame side motor mounts
Again, probably some other things I can't think of
Some advice -
Pull the whole front clip, makes things much easier to get to and install. Just take out the 4 bolts (2 on each side) from behind the door (open the door and look toward your hinges, you'll see 2 bolts holding the fender on), the 2 (on each side) from right under your hood hinges, the 1 (on each side) on the bottom of the fender near the door, the 2 (on each side) holding the inner fender to the firewall, and the two big bolts holding your radiator support to the frame. With another person you can wiggle the whole front clip out (remove the hood if you prefer). I would also remove the front wheels to do so. It's doable with them on, but a little more difficult. Removing the bumper also helps a lot.
If you don't want to remove the whole front clip, just removing the radiator support will also help immensely. Me personally, I'd rather install an engine straight and low than high and at an angle. Makes less of a mess and less risk of someone getting hurt.
Take your time and gather the parts you know you'll need, saves a hundred trips to the parts store
That's my .02 for now
