I used 1/4 inch studs rather than the bolts. I preferr the way they torque down. The thing that made a really big difference is I drilled out the holes a little bigger. I noticed that they never just slid onto the heads with the studs in place. To me that meant they were not lining up and were twisting. So I used a unibit and reamed out the holes. No they slid in place with ease and seal up perfectly. Oh. by the way. I would always use the moroso valve cover gaskets. They are alot thicker and denser. I also learned the next trick from a tranny guy. Use 3M spray tack tp set the gasket into the valve cover. Once set you will never get it off unless you use a scraper. The other is up to you. If you use the 3M it will bond and not let go. You will destroy the gaskets getting the covers off. If the motor is adjustable I would not recommend this. But if the motor is not adjustable, I can gurantee that the 3M spray tack trick is one that won't be beat. Been using this for more that 15 years.
Good Luck
Note If you use the 3M stuff, The parts have to be really clean. Like carb cleaner sprayed clean...