Bob,
There is a ton of ifo on the LS1 Tech website in the conversion forum
http://www.ls1tech.com/forums/index.php
I bought the Edlebrock adapter mounts for my 71 Chevelle and so far the engine is a drop in deal. I also got the GMPP oil pan kit, also seems to fit great although it only holds 4 qts. It is aluminum though and should be pretty easy to modify for more capacity. My older Lakewood Bellhousing bolts up fine along with my Doug Nash 5speed but I only have a bare block and heads so I cant try a flywheel / clutch combination yet. Lakewood does show a different bellhousing for the LS engines but I am not sure what the differences are. I had the one off my small block so I am using it to get the trans, shifter etc in place for now.
Hope this helps,