Pusher or puller fans?

[Number21]

I have a '79 1 ton with a 350. My fan shroud is broken and the mechanical fan is bent, so they need to go. I was planning on installing an electric "puller" fan on the back of the radiator as is normally done.

Then I noticed how much space I have between my grille and radiator. I don't have AC or an automatic trans, so all that's there is the radiator. Is there any particular reason why I shouldn't try to mount "pusher" type fans between the grille and radiator as opposed to behind the radiator? It already runs cold as it is, I think I need a new t-stat....