Wait a minute here.. A stock LS1 hands down creates more torque than any other small block chevy out there. They create as much torque as most stock bigblocks do.
With the right cam choice an LS1 will have a ton of bottom end torque. There are more than a few 450rwtq LS1's roaming around.
Now if you are towing with it, don't use the M6.. The 5/6th gears don't have a lot of meat to them and will tear apart with any decent load.
I'm swapping a LS1 and 4L80E in to my 63 right now. I'd be glad to give you as much info as I can. Also check out LS1tech.com. Here is a link to my truck on bolt, but if your on a dial up it may take a little bit http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=5;t=001127
