The original small block mounts for the '69 aren't exactly like those pictured, so I haven't had any personal experience with them. I have torn a couple of the original style mounts, I also had some that had an interlocking tab, but wasn't able to find them the next time I need to put a set in a different truck.
I haven't torn a mount in decades, even pulled Energy Suspension mounts out of the old '72 K5 that were in great shape when I parted the truck out. Those were probably tested decently by
@Bent77 . It makes me wonder if they put an interlocking tab inside them.
I think that it would be possible to put a catch tab over those mounts anyway, more stealth than a cable.
I never had problems with header clearance on my C10 trucks, but I have seen guys who did. I don't remember what brand hit. I haven't had problems with Hedman or the old cheap Cyclone ones back in the eighties.
I like the look of the POL mounts, would be curious to see how they hold up. I have a spare set of factory mount stands if you don't get a set with that truck, and would be interested in some.