[oldeerslayer]

That's a hefty price for a replacement radiator. I'd definitely return it, since it really doesn't fit properly.
Curious why this will be your 3rd radiator. Doing some hard off roading?

 

[oldeerslayer]

I know from experience that a hose clamped onto unflared lines will, over time, blow off. Repeatedly. Take the time and do it right.
Even on the highway you do need a cooler.
A compression flare will hold and will add a bit of length. I'd put in in a bit back from the end. Retighten it after a couple days.

 

[oldeerslayer]

My bad, I meant compression UNION. It doesn't have to be any high pressure design. The fluid in the cooling lines is under relatively low pressure. @Tranzman can tell you exactly, but I'm under the impression it's under 50 psi.

 

[oldeerslayer]

They only use up about 1/2" of line and add about as much because of the center section.

 

[oldeerslayer]

208 idling isn't anything to worry about.