Clutch fan installation question

Honestly being able to remove the radiator to get the fit better and use studs is best.
I personally have used bolts and flat washers and lock washers because if the locks split at the oval hole… they don’t do their job. Also, small side tip- buy all the hardware from the same manufacture. Don’t miss match hardware. Spinning weight is a real cause of vibration and wear out your water pump / clutch over time. Good luck!
I agree having the radiator out of the car is absolutely the best way! I have noticed how the lock washer splits in the oval hole as well, I will try and see if I can get the lock washer on along with a flat washer to cover the oval hole today, if not I believe I will be using the blue loctite with a single flat washer.