Auto Transmission Shifting Issue Since 4bbl Upgrade

Hey there A body Gurus!

I inherited a '65 Dart 270 Convertible from my grandfather who sadly passed away in 2016. He and I wrenched on this car for most of my childhood and it was a backyard build. I love the car and it is the reason I love cars to this day.

The car sat in my garage for about a year before I decided to do a minor upgrade. It has a '66 273 motor with a 2 bbl carb and ran very rough - was begging for fuel. So I upgraded to an Edlebrock Intake (part #2176) and matching Edelbrock 4 bbl carb (part #1406). I had a mechanic install these to ensure it was done correctly. Transmission is an automatic 904.

Now that all is installed, the transmission seems to shift at the wrong RPMs. I don't have a tach in the car so I can't give you those specs. 1st and 2nd gear seem ok, but 3rd revs high before shifting into gear. I also don't see a kick-down cable or linkage. Shifter is floor shift, aftermarket Hurst.

Would anyone have any ideas where I should start to solve this problem? Is it a tranny rebuild, is it a vacuum line in the wrong place? A setting on the shifter? Or perhaps the fact that it doesn't have any kickdown linkeage? I have to be missing something that's obvious.

My grandfather is probably rolling over in his grave at my struggles...I just want the car back on the road where she belongs! Thank you for any assistance you could provide.