Giardiniera,
Your boyfriend's parents can gift him up to a current maximum of just over €500,000 tax free and so on a house valued at approx. €300,000 now he would not be liable for tax. However, they would need to put his name only on the deeds of the house, and not say in joint names with one parent, as technically this is not seen as gifting the house to him. The Revenue are very sticky on this.
As for his first time buyer status, I am not sure. However, as he has never previously bought a house, and just inherited one, I would assume he would not lose his status. This would have to be clarified.