I'll have to agree, "as cast" the OEM s/o blocks are ready and machined properly for use right out of the box whereas the Genesis/Pond/Shelby requires skilled prep prior to it being useable. I guess my point would be that after proper prep by a skilled, properly equipped machine shop the aftermarket block would hold up to more abuse than an equally prepped OEM block. I think I read that the Shelby block's good to around 2000 ponies. It's not a side oiler design like Pond and Genesis though. We won't even talk Dove, as they wouldn't be a consideration.
The valve train info's very interesting. I'm sure spring loads, cam ramps, which
oil, RPMs etc impact on the valve tip scuffing issue. Are you saying this applies to street driven engines at reasonable (6500 and below) RPMs? Fascinating though, thanks for the info.