67 radiator options?

[blkpny]

Gary, most 14" fans are about 1000cfm, or thereabouts.
I would fit a good single 16" fan, most are 2000cfm, and I've heard there is one that is 3000cfm (unconfirmed).
The general rule of thumb, is that a 16" fan is twice as good as a 14".

[gary70au]

What are the best fan blade designs to use, flat or curved?

Some of the curved ones seem very thin which makes me wonder how efficient they are when flex is taken into account.

[blkpny]

Spal seem to be the brand to beat, at the moment. I'm not sure of whether they are curved or straight. After looking at a wall of fans, on the Davies Craig stand, it seems that they can use either design, it all depends on the particular performance from the size of the unit.