You won't need to load the engine if you have oil pressure problems. I've had two of them lock up when the oil pump drive shafts snapped the splines out of the drives. The engine just starts to slow down till is suddenly stops with a thump according to the operators. Yours is in the category of in the hands of lady luck. It could run just fine for the entire time you want to use it or it could lock up before it pushes a full blade of dirt. There are two converter pressures that can be checked, but the only one that matters is converter outlet. As I recall there is an eight inch pipe plug on the outlet valve on the back of the torque converter housing. I don't remember the spec but I've seen them run between 10 and 20 PSI when at operating temperature. The torque converter inlet pressure is a relief valve that prevents too much pressure in the converter when the oil is cold. I don't recall if the check port is in the transmission case on the transmission control valve or just outside the case on a pipe joint. The cloth looking stuff in the photo reminds me of some gasket materials but I don't recognize the steel plug. It reminds me of a dowel but all the one in Cats that I've worked on were solid through their entire length. Have you figured out if you have coolant leaking into the oil pan?