I made a 666cc engine 4 years ago that was all on the stroke and if I'd have gone to 102mm bore I would have had the same bore and stroke as the 701 engine.
Menno de Jong raced 701s three years ago around a road race track and stuck with 701s because the Husaberg is so light. the engine weighs 26Kg compared to 44Kg so it only has to produce within like 15bhp and it will be even on everything except prolonged top speed.
the Husaberg is still a phenominal engine. even DOHC isn't really needed! for the stroke, the Husaberg valve gear is safe all the way up to your rev max capability.
bore your carb out to 44mm, get a 4" stack on it, my jetting kit and go!
regards
Taffy