Swapping a small block to big block...who's done it?

ok, i know it can be done and most people say it's not a big deal...but i'd like to know from people who have first hand experience or knowledge about what all it takes to install a big block in a small block a body.

my 318 runs fine but like most i'd like a little more punch...i've seen stoker kits for 318's and there are also some 340 blocks out there that can he had at a "decent" price...i'm really leaning towards a 340 but a buddy of mine has a 440 he's let go really cheap. problem is i don't know what all i would end up having to modify to make this happen...

this is a street car and i'd like it to run hard and handle well so i'm not sure if i'm better off just starting with a big block if i'm going to go through the expense of building a more powerful small block.
here's what's in my car now that i think would be relevant:

68 barracuda
318 w/727 trans - trans needs to change to big block?
3.55 sure grip rear end
large bolt axles in rear with 74 dart disks up front

i'm going to be installing new front and rear leafs & shocks soon...any suggestions for a big block?

what kind of issues would i run into...i know schumaker sells the mounts but do i need anything else...are there any clearace issues?

thanks
robert