The usual extra info on this series for the Ferrari 250 GTO...

There are 42 events (36 Trophy + 6 TT) and the rewards 25-50-75-100% are split 8-13-18-28GC.   The LTS-winning PR32.2 gets you well beyond 75%:

The final Cup race is PR 34.8 for which you'll need upgrade pattern 5343343 costing 180GC more, but you may want to try without Body 4 first - the 'integer bug' didn't work for me this time but you might be luckier! 

(For those doing the 250 GTO Monza Laps Team Challenge at the weekend, relevant events are on Tier 8 and 9 and are Road Course)