Ok so I've got to come off the underground tank soon due to a work related move, and have been adapting this 1972 JCB 3CII rad. It's all brass construction, with copper fins. It has 39 flat section brass tubes times by 3 rows staggered (117 tubes total).
Best I can measure is the flat brass tubes are 2mm thick by 10mm wide by 430mm long . the rest of the rad can be seen in the image (which is a link to a bigger one). standard HDD and CD rom included for size indication.
I'm going to connect it up but just for fun any educated guessing / calculations on how well it might cope with my system? assume low airflow with probably around 220 - 250 watts total heat output underload at a guess