I have had many house parties for teenagers. Only one got out of control, all the others lovely with some slightly tipsy teenagers being funny.
I had 30, I probably only knew half of them and allowed all to stay over. What can get out of hand: -
I had boundaries regarding alcohol but I knew some would be sneaked in. However - at one point my house was what some would say trashed (although it wasn't - downstairs not carpeted and completely cleared out, easily rectified with a mop). I found 3 bottles of empty vodka, at least 6 bottles of empty wine. Contacted 2 parents to pick up exceptionally drunk children who could not stand up. Sick everywhere in downstairs loo, several times. One girl sick through the night, - only allowed her to stay because her friends were known to me, sensible and stayed up with her, getting me up when she was sick , as told to during the 2 hours I tried to sleep. Weed was smoked (at least they took it outside). Condoms found in the nearby field next day when we cleared the rubbish.
On reflection I went wrong in not knowing them all (or insisting on contact details) and letting them all stay over - it was this I was most nervous about and rightly so - teenagers act very differently when they are not being picked up by parents.
I fed them pizza - just gave them more energy to continue partying through the night. Fed them bacon butties and croissants in the morning! Some of the boys went to play football and rugby!
That is my experience. Only you know your son & friends circle but don't think the ones you don't know will be like those lovely ones you do. 60 I think is huge, mine went wrong with 30. I think you also have the end of GCSE fever to contend with which will make them more hyper. Have a plan for what to do if it goes wrong. I know one Mum who threw out all boys at 10pm as they trashed her house, carpeted throughout in lovely cream carpet.
I will have more parties but I will take more care to know exactly WHO is coming, with a midnight end for most and only the select few I know can stay-over. DS knows it can't happen again - wasn't his fault but has to take some responsibility for ensuring it doesn't happen again.