Re. the springs, if you have the inboard shocker/spring arrangement the original springs were usually red in colour and about 180lb/in rating. You may find it marked on the end of the spring but to see it the spring needs to be removed. I have gone down to 120lb/in springs which used to be black in the catalogue but when I bought them last year from RHE they were red as well, a new supplier apparently. The car is much better with the softer springs, some people go lower I would think 100 would be the minimum. Concerning the rad, you could fit it in the nose which helps but I found an improvement to be fitting on extra louvre in the bonnet (exhaust) side to let the hot air out.
Peter.