Finished up the throttle linkage and the tranny linkage tonight, glad that's over.
I cut the stock throttle bracket up quite a bit and welded it back together to get it in the correct spot, also added a gusset to it to stiffen things up. The gm tbi has a small pin sticking out of it where the throttle would attach, I ground this off flush where it meets the larger diameter then drilled an tapped it for a 10-32 thread, then threaded the ball stud from my holley carb setup into there with some loctite.
The tranny linkage was pretty straightforward, I fabbed up a small bracket to attach to the lower part of the tbi throttle shaft, attached it with two small bolts and nuts, then added the stud at the bottom again from my carb that picks up the stock tranny kickdown/throttle valve linkage, worked out perfect. The distance from the center of the throttle shaft to the pivot is 1.2" which I copied from my holley carb. The linkage is maxed out at full throttle and has ~3/8" slack when the throttle is closed, seems about right.
I had that return spring on my holley carb as well and added it to the tbi but I'm not sure it's needed, the tbi itself has some pretty mean springs on it, that together with the tranny linkage makes it feel about right, with the additional spring on there it seems too stiff to me. What have some of you guys done for return springs with the tbi? wonder if GM used a return spring in addition to the tbi springs?