The first thing to do is compare what you have now with the stock system. If the shifting was satisfactory when stock, you should be able to achieve similar performance with the new linkage - though you may need to do some adjusting.
First, compare the length of the stock shifter pedal to the new one. If the stock one is longer than the new one, the disparity must be compensated for by the driving and driven crank arm lengths. For example, if your new pedal is 75% as long as your old one, the driving crank arm needs to be 75% as long as the driven arm on the shifter shaft. This will restore the throw and pressure required to operate the mechanism to close to what the stock system required. The other factor is the angle between the connecting rod and the two crank arms. You should start with having 90 degrees between the crank arms and the rod. These angles can be adjusted to offer more mechanical advantage in one direction or the other if for instance you wish easier up shifts. It is a trade off requiring more effort for down shifts.
Based on you picture, I would expect you to need to increase the length of your connecting rod, rotate your driving crank arm clockwise, and shorten it fairly considerably (or lengthen the driven crank arm). Measure your stock and new pedals to find the needed length of the crank arms, adjust the connecting rod length and crank arm rotations to get that 90 degrees, and go from there.