Well there is a lot to look at . What does the cam card say on spring pressures ? What kinda lift will the valve see ? I personally have ran comp 981 on my iorn headed setup. They worked well . I belive they had 115 on the seat and I can't remember open . But u will have to pay attention to coil bind . I also have talked to acouple ppl about runing close to coil bind and was told that you do want to run close to coil bind to keep the spring happy .