Looks good, we did the same and made our old trans cooler into the PS cooler.
We have the new derale cooler mounted underneath the car but cant get any testing before our Charlotte motor speedway roval race. So we did the sensible thing and left the other two coolers and now we have 3. We did take it out of teh radiator since we are pushing the motor harder and dont want overheating issues.
if it cools fine then we will eliminate the smaller cooler and then keep going until there is 1 or all three still left. The temps have been fairly mild at low 90s but it very well could be 100 ish so who knows.