Surf rudder

Do spec skis have standard, typical style rudders (length, shape)? There has been positive talk about Epic's elliptical surf rudder, which I assume is for open ocean, off shore, downwind "surfing." Would you use this elliptical rudder for surfing the inshore waves that surf boarders surf? Not the waves that crash on the sandy shore, but out a bit. I enjoy riding these steep waves breaking toward shore on my sturdy fiberglass 2004 Fenn XT, but I broach (spin out, get sideways) a lot. It has a 7" standard rudder. I noticed an old spec ski of mine has a much longer, swooping rudder. It will not fit my XT, though I suppose the extra length would help. I do not surf the spec ski because the footwell is too short.
If spec rudders are typically very long because they surf the steep onshore waves, then I will look for a long, "spec ski rudder" for my XT, maybe from a Fenn Tarpon, assuming Fenn shafts are same length (5") across models (huge assumption, I know). If "surfing" is "surfing", regardless of off-shore or on-shore, I should try to find a 9" elliptical rudder with 5" shaft.
Any other suggestions for getting a replacement rudder for my XT? Needs to be 5" shaft and I cannot make my own and there are no shops around that could alter non-fitting shaft.
Thanks