ls engine swap
there is a spacer for the trans, gm sells it. you will also need a different flex plate. if you don't, the torque converter and pump will fail because the torque converter doesn't fit into the rear of the crank properly so it isn't centred. the early 6.0l vortec with the 4l80e trans is the only one that accepts an early gm auto trans without a flex plate adapter or spacer. these vehicle came with the gm spacer and bolts and that factory flexplate. these are basically the same components needed for the older trans swap, just done at the factory. (copied from the book "how to swap a gm ls series engine into almost anything") you have to use a spacer with longer bolts, or a custom torque converter that has a longer crank hub.bowtie overdrives makes the torque converter that is custom fit to mate up to a stock flexplate. in my opinion it would be better to use the tans and engine combo from whatever the donor vehicle is. get the computer to go with it because they are sort of matched up as far as sensors etc. you may need to get the stock computer flashed when you are done to eliminate some of the stuff you won't be using, like air bags etc. there are several sites to check for that. LS1Tech is a good one.I am putting a 5.3 engine and 4l60e trans in my 57 gmc, so that is what I will be doing with my engine trans combo. haven't got as far as the engine yet. still working on the frame so far.
the how to swap book is ok, there is quite a bit of stuff on specific swaps like into a volvo or a bmw. it does have some basics on stuff like the trans swap and info on what engines are better and what they came in. i have heard there are better books, but the guys on the ls1tech site would maybe be able to help out there. there is a forum there as well.
have fun, kep us posted,