It has been years since we worked with W2s. There were three different valve angle that could be obtained. The 18 degree heads were good, used standard W2 rockers and worked with either a 59 or 48 degree block, flowed about 250 CFM @ .700", the 15 degree heads were better---could flow up to 290 @ .700" if "prepped" properly---but required a 48 degree block and special "oil through pushrod" rockers(Jessel). There were a few sets of 12 degree heads---primarily through Stanton that were real good but required T&D rockers.