I put it into gear and it dies.

The trans kickdown won’t affect this. Yes just wire it open for now so you can drive. Don’t drive with it sitting at idle setting it will kill the trans in 200 miles.

is the heat crossover in the intake plugged or open? If it runs a few minutes does the intake crossover get hot? Don’t burn your fingers feeling it, should get hot enough to burn off paint after driving.

This passage plugged on a stock engine will make it run terrible. seen it many times.

What carb do you have? 900 Idle speed is to high and it is that high to compensate for problems.

advance the timing until it misfires and back it off slightly till it smooths out. Turn dist CC to advance.