i had a 99 LS1 and considered beefing it up...priced the kit etc....
I agree with Greg..you can purchased a complete Long block cheaper and less hassle than building one....
just for the record the difference bewtween a 350ci and a 383ci is the stroke..which requires new crank Rods etc......
thats why the 383 are called strokers,,
just pull up anything to do with 3rd and 4 generation camaro's and you will see all the stuff they offer...
i was going to place a rear mounted turbo (STS) on my 99 ls1 before i decided to sell car...
check out this website..i know the owner bruce really well..lives near by.
http://www.hawksthirdgenparts.com/
Brian