Do you see that being too much for the case to handle?
For use, I don't think so as long as the radiator itself is on the inside; but it depends how often you dig around inside and have to remove it. If you want the radiator mounted on the outside it may get a bit tipsey.
You could fill a 140.4 worth of rad with water and hang it from the side using masking tape or what not to see if the weight will cause it to easily topple.
If you'll have fans attached to the rad, there's no point in making the case air-tight. If you wanted to just use the air pressure from the intake fans without exhaust fans on the rad, you would need to.
If it were me, I'd put the radiator on the inside and one set of fans on the outside in pull-only. Cougar HDB 140s to keep it silent, specifically... or reverse the whole thing and push-only for a little fresher air.Edited by Electrocutor - 2/4/13 at 4:54pm