Auxiliary Transmission Cooler Placement

1.) If you want to keep that trans cooler, move it to the front of the radiator. Keep it at least an inch away from the rad., more if you can. Keep it towards the bottom of the radiator, exposing as much of the rad. core to airflow as you can. A reasonable street driven 727 can live fine with just the rad. cooler, a worked 904 may benefit from the additional cooler. In general.
2.) Get rid of that 4 blade flex fan. That thing won't move enough air to float a paper airplane, let alone cool a bored 340. Try something like the MP viscous fan package, Mancini Viscous Fan Package Six or seven blade, hunt for your best deal. Try to space it about an inch from the rad. Fan should be 50% in the shroud.
3.) Matching fan shroud to the fan Mancini Racing Radiator Fan Shroud Again, hunt for best deal, new or used... links are for reference only, not endorsing anybody.