One of the best things with the FiTech - return springs are on the butterfly shafts.
No need for multiple return springs in all directions getting in the way. Really cleans things up.
I believe you can wind them in or out as well if needed, but they work as is for me.
I would think carbs would have this modern marvel in 2019.
As far as drilling your manifold again, the tbs have two sets of mounting holes, not sure what the other set is for, but maybe you wouldn't have to re-drill.
You could probably sell your linkage and have enough to cover any costs converting to inline.
There is 1 dual quad inline linkage out there, it's crap and pulls from below the tbs, it ended up bending my rear tb tab. This caused issues with the IAC settings, forcing the 2 tbs to be out of sync. Once I added the $20 linkage I could adjust the front which would move the rear the same amount, then adjust the rear until it pulls the front, then back it off. Possibly an inline benefit, definitely an issue where I had to remind myself to use the kiss principle and not immediately blame the efi.
I recently put new bolts in with lock nuts, and brought the cable stud out farther, need to trim the ends still. Also added the gauge right on the tb, clean and simple, although it can't be indexed, it's highly visible from the driver's seat. No additional lines either.
I had to modify the end of the Lokar cable, but it was very easy.
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