I have the 212/218 .558/.563 114 LSA and it works great with the radix, pulls hard from 2500 RPM and up, I really don't have dyno numbers, but the truck is definitly faster, I'm very happy with it. You'll also need the 918 springs, pushrods and tunning.
I think Flyer has a bigger cam with the Radix and he was happy with it, I don't know the specs but I guess he'll post it later.
Thanks.
STOLEN: 2005 SILVERADO 1500 4WD ECSB 5.3L 3.42 gears
Sold: 2003 SILVERADO 1500 RC STEPSIDE 5.3L 3.73 gears