35 mph WOT power loss

I seldom say this, but I feel I need to;
Get rid of that Metering-rod carb;
There is likely nothing wrong with it, but it is a terrible carb for a newbe to learn tuning on.
Get yourself a 650DP; set it and forget it. Yeah it will likely be rich; but it will fly. And it may not get decent fuel mileage. But it is an easy carb to learn, and has great throttle response.
Once you get the Holley tuned, then you can go back to the Eddy.
Btw if you buy a NEW 650, order a 10.5PV, and a tuning guide, along with it.
Nothing wrong with a used one tho, put up an ad on FABO and see what pops up.

As for the KickDown;
On 1970 and older V8 A904s the KD was set to to downshift with the pedal on the floor. It had very little to do with rpm or speed, so long as the governor pressure did not interfere.
On 71 and newer A904s, You could adjust the KD to downshift at part-throttle, so that you didn't always have to floor it all the way. This is IMO very desireable.

The governor, if you are still using it, needs to be matched to the rear gear, as it only has a limited amount of adjustability. So if your gears are different from the ones your trans is tuned for, then you may have to modify the flyweight or buy a kit from A&A or such. If you don't know anything about transmissions, then there is not much to be seen by dropping the pan. Adjustments, except for line-pressure and bands, are all done by swapping out parts.