The oil pressure regulator valve is part of teh oil pump assembly, inside the engine.
A more likely cause of high pressure would be installation of too heavy of an oil (10W30 is the recommended oil for this application). USing a 10W40 or thicker oil will cause a high pressure problem.
70 psi is not usually enough to create any leak issues though; engien oil filters and oil filer gaskets are easily able to withstand this amount of pressure. I suspect that possibly your oil leak is occurring higher up at teh gasket where the oil filter boss (the threaded piece that the filter screws on to) attaches to the engine block. This threaded part screws off of the engine, and there is a gasket and an O-ring located between it and the block that can develop leaks after many years. It is possible that you may have accidentally loosened the threaded aprt during the oil change, especially if the old filter ewas overtightened or stuck. The repair kit to reseal the filter boss costs about $4 at any Dodge dealer.
I hope this is helpful; if so, please click my accept button and leave positive feedback! Thanks!