Solid advice from everyone here.
Not sure about the desire for 3hp, but you already have the 15.15 (assuming dell SHA) carb, eh? Read the MA history lessons for v1's.....or take the short cut:
Port that stock cylinder intake to match and taper that down to the port window. Raise your exhaust port window 1 mm, widen 2 mm (1 mm each side). Lower your intake port window a smidge (technical language). Grab a cheap tomos techno bullet pipe, hack and weld to fit, then match your exhaust port to the pipe and taper that down to the exhaust window. Even with stock gearing (assuming 10 x 44) you will be in the 35-40 mph range and blast off the line with this recipe (assuming your wheel bearings aren't garbage, your chain isn't rusted, yada yada, and so forth.)