If you are buying his house and want to buy it with a loan, you need to apply to the bank and have it evaluated by an appraisal company. This method requires you to go through the property rights transfer procedures with the housing management department. As for the risks, if you follow the normal procedures, there is no risk in terms of property rights. As for his request for a bank loan of 300,000 yuan, it depends on the total transaction amount and appraised value of the house.