i had a 1936 bmw 250 single cylinder. it had a low pro tank, maybe 2" above the frame rails. i would turn the battery sideways (like a fwd car, transverse mounting). if you like the angle of your design's backbone, might i say add some non-skid strips? it looks like you are planning on using some really old-school handle bars, like from the board track racing days? you could set the motor a bit lower, like between the frame rails. maybe a peri-scope so you wouldn't strain your neck? the geometry is all wrong for coming to a stop. you wouldn't easily be able to get your feet back on the ground to keep you up. also figure out where your airbox and or carb are going. solely as a dragbike, it may be ok, but not a daily rider. hope it helps