I think you will be fine with a two row aluminum. Now I have an A&C also
http://www.priveye.com/cobra.htm and I am using the 19 x 26. I started out with a Griffin from Summit for 185.00 but that one started leaking after about a year or so.
I went to Afco Racing
http://www.afcoracing.com and they took one of their standard aluminum ones and modified it. They put on -16AN fittings top and bottom, blocked off the filler cap (you don't need it) and added a draiin petcock. Total cost was around 255.00. They did a nice job.
I plumbed the system with -16AN and use a 180 thermostat.
Roscoe