A: stock 01 LS1's normally dyno at 300-310 rwhp B: you're probly somewhere around 330 rwhp right now Ci stated that 10-15% of 01's had ls6 block, not 10-15% power loss, that was in regaurds to SOMSS) D: like you've heard much by now, the z06 setup isnt gunna cut it enough, you may want to go with a slightly bigger cam like i suggested earlier( the stealth MTI cam's get decent numbers and stock idle sound), anything with high LSA will keep the smooth stock idle(if you really consider it smooth lol, but it is compared to other cams), you may want to look into porting your stock heads or even maybe getting some 5.3 heads and porting them out, therefore upping the compression and you'll get more torque that way and horsepower.

Cliffnotes: I think if you do a mild cam thats a lil larger than the Z06 cam but with higher LSA(such as the MTI stealth cams), and a pair of good heads such as 5.3 which would increase your compression ratio or good ported 5.7, and you get full bolt ons including everthing(even LSX intake and throttlebody maybe, even though you have the ls6 intake manifold), if you stick with the ls6 intake manifold get the throttlebody ported, get some high quality longtube headers(kooks or QTP), SSRA, full suspension(even though it wont show on the dyno it'll show on the track and street), tires, 12 bolt with 3.73's(since you have an auto), higher stall will help too from a dig, some new roller rockers and full valvetrain upgrade since you're doing engine mods, lid, filter, and a cutout(just a suggestion for when you're gunna really go for it at the track), i think with all those you'd be a good contender for the 400's