1/2" Heater Hose Fitting

Does anybody know who sells an Intake Manifold fitting for a 1/2" Heater Hose on a 340? The fitting would need to reduce from 5/8" at the Intake Manifold to 1/2" for the Heater Hose. I bought Mancini fittings, but the Heater Hose fittings are 5/8" on both ends, which is fine for my 5/8" Heater Hose.

Thanks