L98 Corvette Heads
 

How much lift can stock L98 aluminum heads take?

they have screwed in studs which is good but the stock springs are only good to about .460". I just put in an lt4 hot cam (.492 lift) in my vette l98 and new springs that are advertised good to .570 but i wouldn't trust them over .520. I also had my valve guides and the collars on the spring cups milled .050 to clear the retainers.

here are the springs i got, the competitors "2300". they are standard diam. so you don't have to mill the spring seats:
http://www.competitionproducts.com/page24.html