When I measured the pipe from the flange to the start of the chamber mine was 13" measured on the outside of the curves it did look link of like a horse shoe. I made it 13" form the start of the exhaust flange to the start of the pipe and I do think it needs to be shortened. to 11" I just hve to do a little cutting and welding.
its not real hard to do the changes even if you don't match up the transfer ports cylinder to crankcase. the toughest part was the intake manifold and that was because I used stainless steel tubing and mild steel for the flange witih only a oxy act. torch its very tough to get a good weld with out pin holes stainless is onery with the wrong welding equipment/gas.
I'm not working on it for a while as I'm worn out from all the playing this week end doing that bike, mowing the weeds, and PMing my Harley.
Sometimes I can change oil and never spill a drop well not this weekend every time I turned around I was sloping Royal Purple Syn oil all over the place
even the new oil I spilled it. The worst was pouring the used oil into a gallon jug and having it tip over on me I'm not squeaking anymore.