You need to make double dog sure that your bolts aren't bottoming out in the head before they reach torque. I have seen where a too-long rocker shaft bolt torqued into an AL head knocked a hold in the port/water jacket below the bolt. It will cost you very little to convert to studs and you get better clamping (since you use all of the threads) and you don't need to worry about bottoming out--JMO
http://www.supermotors.net/vehicles/registry/9026
