4.3/5.7 swap

[chevyfan87]

so, im not necesarily(sp) going to do this, but i have done my research a little bit, but havent found what i want. i have a new style 2000 gmc sierra 1500 with a 4.3 automatic...i was told that if i wanted to do a v8 swap the 5.7 would be the way to go because they are actually from the same gen and it would drop right in...but as these trucks did not come with the 5.7 what about my exhaust? will my stock exhaust work with the 5.7 manifolds? if i run headers are the flanges the same for a 5.3 so i can use 5.3 headers on a 5.7?

any input is helpful...