hi,    whats wrong with the sporty rocker boxes ?

hi, i think pushrod to rocker spacing could be differ  also  frame & carb  clearance ,  i know early sporty evo heads where the pushrods  go are differant spacing e.g.  1986 1100 to 1991 up 5 speed  & 1200 the spacing is about  1/4 diff & the pushrod tube o'ring is at a diff angle , just enough to stuff you up   because 883 head chamber the valves are closer together than a 1200 ,                3'' bore as to  3 1/2",      you would have to realy have a good look