usepyproj.py

from rasterio import coords
from pyproj import Proj, transform

## bbox from input
bbox = coords.BoundingBox(left=-2699073.2235329347,
                          bottom=-1588806.0694413616,
                          right=2697926.7764670653,
                          top=1588193.9305586384)

## custom crs
inCRS = {
    u'a': 6371229,
    u'lon_0': 262.5,
    u'no_defs': True,
    u'y_0': 0,
    u'b': 6371229,
    u'proj': u'lcc', u'x_0': 0,
    u'units': u'm',
    u'lat_2': 38.5,
    u'lat_1': 38.5,
    u'lat_0': 38.5
}

frProj = Proj(inCRS)
toProj = Proj(init='epsg:4326')

#get lower left coord in WGS84
x1, y1 = frProj(bbox.left, bbox.bottom)

projected = transform(frProj, toProj, x1, y1)

# def not printing the correct coords
print projected