Uh... What? Splayed Valves make the engine more reliable thats a new one. If you are talking about splayed bolt caps, Buick blocks are deep skirt blocks that don't lend themselfs to having splayed bolts on the outer main caps. Not to say it can't be done but hardly worth it, and very hard to find a block that hasn't already been converted to a 4 bolt cap if it can be. The splayed valve heads just flow better because they move the valve positions and angles around so that you can get get the valve farther away from the chamber wall so you get less shrouding. Nothing what soever to do with durability that I know of. Then again I don't build engines, I just read a bunch and apply my engineering and science background.
I was half asleep when i done the post sorry. What i mean is some one should cast a head like the sb2 v6 chevy everyone keeps wanting to make blocks i would like to see a real good head like the s2 thats the only place they got us.