The only pedal that matters is the gas pedal if you go DBW. If you go cable you can use stock 2nd gen pedals.
Cross member - lots of options out there, including modifying your own
Also lots of mounts out there. Good reports form the edelbrock mount/header kit for 2nd gens. Some guys use stuff made by BRP but I'm not impressed with their stuff. Some of this comes down to how much you want to spend.
I've read more about 1st gens, and for those a lot comes down to matching headers & mounts. Some headers fit great if you use mt 1 but not with mt 2, but another set of headers is the other way. However 2nd gens move the steering box in front of the engine so I think that alleviates some of the issues.
I still think the most difficult part is a good fuel system that doesn't choke on exit ramps under 1/4 tank.
Search this forum:
http://www.nastyz28.com/forum/forumdisplay.php?f=49
And of course here:
http://www.ls1tech.com/forums/conversions-hybrids-28/