The usual extra info on this series for the Lancia LC2...
There are 42 events (36 Trophy + 6 TT) and the rewards 25-50-75-100% are split 9-15-20-31GC. The LTS-winning PR97.1 is more than enough to reach 75%...
...but obviously you'll need to upgrade the car further to complete the series - the last cup race is PR99.6, which needs an upgrade pattern of 5533333.