The first question is which carbs are you using?
There are a number of aftermarket adaptive kits but they are carb specific. I'm using a 700R4 in my 153" Chevy II four banger with a handmade tubular ram intake and a NASCAR 390 Holley and it works flawlessly!
Your best bet is to have a REAL transmission specialist set up the cable linkage. THEN you won't be dependent on expensive electronics. I love some of the electronic controls and the like, but they ARE prone to stacking small anomalies into major malfunctions at times.
