what adjustable rockers need no guideplates

is there an adjustable roller rocker that does not need guideplates. if so what type are they. are they rail type on not. i need to understand the different types of rockers. i have some 289 heads without guideplates and i don't want to get them machined for guideplates. i think they used rail type rockers but i don't know what rail type is so i can't be certain. can somebody give me all this info. thanks. http://store.summitracing.com/partdetail.asp?part=CCA%2D1431%2D16&N=115&autoview=sku

ok i found some roller tipped rockers that do not need guideplates, but summit says they only fit on 1968 289 heads, is there a reason why they wouldn't fit 1966 289 heads. and don't see a reason why i can't reuse the stock HO pushrods, do you. and also is there a full roller rocker that i can use without guideplates. thanks.