A 75# Dorado would be a record on a fly (I think). The two fish fight differently and while I am not an expert, I have caught a few over 35# on an #11 and Dorado are tough. Powerful runs and then a long pull to get them up. 30-45 minutes is not a long fight with the bigger fish.
Tarpon seem to explode, jumping and tiring themselves relativly quickly. Having said that, I hooked a 100# Tarpon last year in Chockoloskee that didn't jump once. Ouch! I fought that fish for over an hour befor I lost it.
I think that this would qualify as an apples and oranges situation. Eddie