Would my Duster run cooler with an electric puller fan?

Just got my 1970 Duster 340 the other day.
Had to drive it on the highway about 20 miles each way today, and it ran very hot (one line below H on gauge). Outside temp was around 90, and on a wide-open highway cruising at 65-70.
I never had an electric fan, but do know a lot of cars use them down here. It is at least 90 every day from late May through early Sept. My '70 Roadrunner I just sold never got hot, even on the hottest day, but it had the 26" fan and shroud. The Duster has no shroud. My radiator is 22" wide and I would appreciate comments about the benefits of changing fans. Also, which brand is good, I don't need the "best".
Also, what is the price range I can expect to pay, and what size fan is recommended?
Here is my setup:

The car is recently totally restored, new water pump, radiator done, etc.
It did come out of Canada, so I will check which spark plugs are in it as suggested below. If I decide to change plugs, what plugs are recommended (brand,size and gap).
This is a stock rebuilt 340.