Hop over to the full size Chevy forum. They have hundreds of pages in one forum on the 96-00 vortec 454. I've got one in my 98 k2500. There was a guy early in that thread that got something like 600 hp out his l29. It cost money but it is possible to build power with them.
Lots of reading here:
http://www.fullsizechevy.com/forum/f...Vortec-owners=