The 4300 requires a simple tool be fabricated to check the level of the "pontoon" type of floats, and most applications are 13/16 in my experience. Do you have the secondary needle and seat in yours? If so there are two float levels to set.
1965 "K" GT fastback Honey Gold exterior, Ivy Green and White Pony interior, many options
1966 Conv., high option, removeable hardtop, thermactor "C" engine, AC, Springtime Yellow exterior, Black Pony interior
1968 California Special, "J" code, ,many options, white with red interior