If anyone here had actual experience using that particular repair kit then I'm sure they would have mentioned it. As to whether it's worth a go or not, depends on some of the things discussed in the thread, such as it the linkage that is foobar or are the flap valves actually stuck in place, etc. But it doesn't look that expensive so I guess it would be worth having on hand when you go in. In the OP you said 'Among the codes...' What other codes are present?
Specifically I have never installed one for the reason I have explained in my last text posting, (i.e product improvement) but that's not to say I haven't seen it applied to an engine we have had to repair.
First of all, for me running a shop business its essential to make sure the EKAS manifolding is in good shape and likely to live through the unrelated warranty period of say oil cooler/HE repair without faulting out, otherwise it will be a comeback.
In short comebacks are costly, and I have calculated that even a simple comeback costs the business a $175 minimum overhead.
We have fixed countless numbers of these engines with EKAS related issues or having discovered during tear down, that they won't go the distance without further wear related failures . So we have to go back to the customer and explain that further replacement costs are involved in the execution of a successful repair being a matter of expediency.
So I can remember now in the mist of time, two such modified EKAS systems which were pulled out and found to have been modified using these linkage arrangements.
I remember the arms were really very worn on fulcrum holes on one and the other had sheered off the arm at the base off #1 cylinder inlet port probably due to a seizure.
I suppose was installing the metal linkages a matter of expediency to recover an largely worn set of EKAS linkages and save $2500 being a salient question.
For a possible answer?
Probably since it worked for a while and then failed with a new owner having to foot the bill for new manifolds.
Since we BG purge such engines before teardown there is a strong evidence to suggest a flow bias exists within the manifold set .The passenger side getting the better air flow on (LHD units ) and #1 cylinder the front left side being the worst.
Since the A side EKAS always seems to fail first by propensity, the answer to some of this probably lies somewhere with air flow since it ends up being a dirty bugger, when having to fix it if it does short trip cycles as an operating norm .
Dennis.