Yes, you have to shorten the tops of the valve guide bosses for more than .450" valve lift. The inner diameter of the spring pocket is too big for most replacement springs with a damper also. (some people just remove the spring damper) You can machine the valve guide bosses and spring pockets using comp cams tooling and drill arbor and a good electric drill.

Decide what valve spring/retainer/seal combo you'll be using a get the tooling nessessary. The rocker arm studs can be simply drilled and roll pinned if you don't need/want pushrod guide plates. Then use a self aligning rocker arm.

The numbers you posted are not the ZZ4 cam specs. 208-221@.050" .474-.510" lift 112LSA is....

F -BIRD'88 I was misstaken on the LSA it is 110 . Will use GM PN10134358 Springs

 

http://www.2quicknovas.com/vortecheads.html

http://www.chevyhiperformance.com/howto/97458/photo_13.html

http://www.popularhotrodding.com/enginemasters/articles/hardcore/0511phr_vortec/index1.html

http://www.popularhotrodding.com/enginemasters/articles/hardcore/0511phr_vortec/photo_04.html

http://www.popularhotrodding.com/enginemasters/articles/hardcore/0511phr_vortec/photo_02.html

http://www.chevyhiperformance.com/howto/97458/index.html


http://www.carcraft.com/techarticles/vortec_valve_spring_upgrade/

 

Vortec

Thank you for the info. Tooling has been ordered