You may be right about the dipstck tube. While I don't think this is the cause according to your description, a common leak on the passenger side comes from the upper hole on the front of the block by the fuel pump. It needs to be plugged with a short bolt or it will leak oil past the fuel pump pushrod and be blown down the passenger side. It's often mistaken for a leaking front crank seal or front oil pan gasket.
'79 Cutlass - 305, '66 El Camino - 400, '35 Ford Sedan - DOHC 4.6, '35 Ford pickup - 283, '72 510 wagon - Quad4, '82 Goldwing - 1100