Hello Sir, First of all congratulate your son for getting a great percentile. If you are proud of him then all you need to do is support him in thick and thin.

And answering to your questions, recent update says, that JMI could be good fit if you are looking for admission in Delhi itself. If you don't want in Delhi, then there are many colleges near Delhi, that will give your sone a good opportunity to shine by doing Bachelors in Architecture. Other than that, there is SPA Delhi, but it has a (general category) cutoff rank in Architecture of 230.

Again, all the best to your son.