how fast can it go

As to your orignal question..I have my 2 H's and my super H turned up to around 2100-2200 rpm. I never let it run that fsst under no load. Plus I only use the extra R.P.M's for no more then a min or 90 seconds. your engine sounds like it will be fine turning her up a bit. I Turned mine up so i could get a head start on steep hills in road gear. It made a diffrence as my 43 H that is medium compression would not make it up this one hill on my way to dad's farm. After i adjusted the valve lash and turned up the r.p.m.'s she makes her the whole way. I really like the extra speed on my super H. we go on hay rides and if a dog starts chassing ya i can hit 20mph with my super H and no dog i know can go that fast for more then a few seconds. (at leat farm scraps eating dogs that are around here) Good luck. Also mabey find a good used after market govner like a M@W there more snappy and that give the engine a "head start" then make the spring shorter till you get a few hundred extra r's out of her. Also adjust the carb to run MAX power. I have mine turned about a full turn to a turn and a half out from its "starving point" I like to test it going from an idle to wide open as soon as it dosent studder going up giver a full turn extra. Might wanna run a hotter plug I now run autolite's equal to champion d21. Good luck. take her easy and have fun, stay safe.