I'd rather see a fixed bar, rather than an attached link just to save reciprocating weight (those roller are heavy enough!), but there must still be something very definite on the lifter body to be restrained.
The original button or lug could be used, with a fixed plate slotted to allow the lug to travel vertically, but it's got to be pretty strong, absolutely straight/parallel, and hardened against wear. Since it doesn't move, the plate can be attached in several places. The height is obviously the lobe height + safety factor for strength, perhaps 1/4" on either end, so .500" lobe needs a 1" plate minimum, etc. Thickness: same as the lug is probably safe, but stiffer if it's solid behind the slot.
However: I'm not sure where to attach it. There are no flat vertical surfaces inside the pushrod compartment, no available threaded bosses, nothing substantial to tap. A single strap or plate could run the whole length and tie all 12 lifters together, but it's got to bolt somewhere.
If you had the nerve, you could just bolt it into the inside of the pushrod cover. "Hang" it in place on the lugs, its several studs protrude out beyond the gasket edge and through the wall of the modified cover. Slip machined spacers on the studs, put the cover on, put nuts and Stat-O-Seals on the studs.
