If you’re in Rome and want to visit the tomb, just take a train from Roma Termini to Orvieto. You can spend the day there and see the Eucharistic miracle in the Cathedral, have lunch and enjoy the town. Then, just take a taxi for about 50 euro (or take a bus that leaves just once a day) to Civitella del Lago. My taxi driver was great. His name was Olinto Rossi and he explaind that he knew the Bugnini family.