I am in the middle of doing a 305-355 swap and will be ditching the tbi for the fast ez efi. I will still be keeping the stock ecm to run the gauges in the car, will the ecm still be able to control the lock up while not managing the engine or will I need to run one of the available or make my own tcc lock up kit.

 

Gauges run direct off the sensors on the engine ( or the coil in the case of the tacho ) ; not the ECM

The ECM would have to have all the same inputs it does stock

Just install a 4th gear pressure switch in the trans valve body; anytime trans goes into 4th the convertor will lockup.
https://www.thirdgen.org/forums/carb...c-control.html
No need for any extra or manual switches