Those intake seals are actually most important because they can suck oil through and it goes right into the combustion chamber with fuel and gets burned and then out. Though if the engine didn't burn a lot of oil, they should be ok. They can be change without taking the head off too. Air pressure shot into sparks plug holes using an attachment for the airhose will keep a valve closed so they don't drop into the engine when removing spring keepers. That, or raise piston up enough to keep valve from dropping into cylinder too far that it can't be retrieved. They can be done another time if time is too tight.