Joe, the machinist gave the option of using either bronze guides or liners. He hasn't had an issue with the liners in 19 years. I gave the okay for the liners. If the shoulder/step for the spring locator is eliminated, I could use LS hat-style viton seals that have a built-in ID spring locator that should work. 

Keep in mind that we're talking about iron heads on an engine that won't see 6000 rpm. Horsepower? Maybe 300.

A couple of points.  If you cut the guides down you will have to cut them far enough for a hardened spring seat cup or spring locator cup.  There is a cutter for most spring od sizes and guide od.  On my iron heads(3 pairs) I cut them for bronze guides, which eliminated the step for spring locator.  You can sink the spring seat~.035"  without a problem for strength, but you will need to od the cut for a spring locator cup.  You can also cut the guide od for different size PC seals(.500/.530/.560")  but you will then need the spring cup locator to be able to fit over the guide and it needs to be snug.  Lastly, some folks don't think you need a hardened spring seat locator, just a spring shim. The beehive spring needs to be stable and not walk around, so I found the seat cup/spring locator to be the best answer to keep the spring from moving.  Make sure you have plenty of seal to keeper clearance, and coil bind clearance of at least .050".  Joe-JDC

JDC

In Ted's article, "A Tale of Two 330-Inch Y-Blocks," Isky Beehive valve springs were used on the ECZ-G heads. According to Isky, the bottom OD is 1.290; bottom ID is 0.885. The top OD is 1.055; top ID is 0.660. 

I plan to install Pac 1283 Beehive valve springs on my ECZ-G heads. The bottom OD is 1.250; bottom ID is 0.845. The top OD is 1.085; the top ID is 0.845. Should the cylinder head shop have any difficulty cutting the spring seats for the Pac springs?

I almost forgot to say Happy Thanksgiving!