Hey bro, I just seen this post. If you need any help let me know. Yes I did try the 6.0 manifolds backwards and they did not fit because of the flange. if you do like you said (cut the flange and weild some v-bands on there that should work fine) you could alway move the steering shaft over alittle bit to clear. the manifolds where touching the steering shaft aswell. If you need another oil pan, I have 3 sitting in the garage. Good luck. you seam to have more time than I have. who are you going to have tune it? I use Rick at synergy. He has a stock 5.3 (block and pistons) pushing 814hp 800+tq. you will see his post on ls1tech and performancetrucks,net. The key is tuning to make these stock motors live. I also had my stock block 5.3 pushing 680hp 780tq. PM me if you want to come by and check out my progress. Or want to check your mockup. I have truck manifolds and my motor is sitting in the truck. you could check your clearences if needed...
