46RH A518 transmission radiator cooler ?

[rustytoolss]

I will be replacing My 727 with a 46RH A518 overdrive unit. I will be replacing the cooler lines to 3/8". Would it be OK to run the fluid through the stock radiator cooler , and then into a large external cooler with 3/8" line size. I get that the stock cooler would create a flow restriction. But by then going through a larger external cooler, would that offset the restriction. I would like to keep the stock cooler if possible.

 

[68-500]

Im not saying it would hurt but, Im not sure it wouldn’t hurt it. Best talk to transmission builder. Maybe the stock cooler could be upsized by radiator shop?