Originally Posted by engineczar
CompCams 26981-16 will fit with no machine work.
Sure will. There are other drop in springs for the Vortec heads that allow more lift w/o any machining needed, despite what you may read.
Two beehive springs from Comp are p/n 26915 and p/n 26918.
Another spring that works w/o machining and is recommended by GM is the Crane Cam p/n 10309-1 drop-in valve spring/retainer kit which is good for .550” lift (this allows about 0.025" between the retainer and seal).