For reading about radiators, ie. heat exchangers, I recomend Compact Heat Exchangers by Kays and London and from there look to any other heat exchanger book you can find in order to fill in the neccesary information to design the radiator. As for building a radiator, try and find a local radiator shop and they should be able to build one to the specs you want as long as certian dimensions are close to normal like fin height and tube sizes.

Hope this helps.

before you build your engine if you have alreday decided on the HP and location of engine running,water pump discharge fan design either motor driven or shaft driven you can pick  araditor from the shelf or after discussing with your local rad. man/sevice shop.
this will reduce your time to pick a radiator and fix the right one. since your enfine is going to stable you need a Heavy duty radiator with more water capacity and a fan desghn which pushes air out thru. the radiator. hope this will help you