i can't give you any tips of how to do a radiator your self, but i can suggest you that instead of buying a new radiator for a lot of $$, go to a junk yard and find a second hand heater core which will cost much less $$.
some tips for your w/c, try not to mix metals, if you block is going to be made of copper, do not buy an aluminium heater core, try to find a copper/brass one
