The blocks are cast for both standard and raised cam locations,as stated the cam tunnel bore is located at different height.The casting can accommadate standard,55mm and 65mm Ford and aftermarket bearing including rollerized cages.The only modified considerations are the rear bearing diameter and if you rollerize then the front bearing bore should have a support welded in the upper top half for strength.If a block is in question just measure the crank bore centerline to the cam bore centerline and check against a stock block.I don't recall the exact difference in measurement but it's alot.If your going to a raised cam block the you should consider moving the lifter bores.Stay with the standard location unless your planning a engine over 605"