Is car auto or stick?
Smokes under load only.Correct?
Colour is white-as in blown headgasket?
Might be your vaccum modulator.
It controls the upshifts of the autobox.
If you follow a rubber hose(small) ,at the base of the carb,it connects to a pipe-leading down the pass side of the car.
There it will be connected to a hose again that goes to a funky looking canister.
If you disconnect the line at the base of the car-temporarily-,and the smoke vanishes,you have a busted diaphram in that modulator.
A new modulator is VERY cheap and VERY easy to install.
What gives the smoke in that case,is the motor burning auto fluid.Very characteristic white smoke.
470 cubes of fogger injected thunder in a 71 z.