Thanks for the response. Did some more crawling around and searching the web. The trans is exactly like pictures I found of a SROD with internal rail. I have not heard good things about this tranny except that it gives great gas mileage due to the overdrive gear for 4th. Can it stand up to 300 plus horsepower and torque? I doubt it as it was meant for V6 Mustangs etc.
Engine is definitely a FE or FT (truck version of FE) and yes the intake (Edelbrock in this case)is molded into the head. I hear the casting number can be found if you take off the starter so will try that next. Seems someone moved the whole drivetrain ahead 2.5 inches to get the oil pan to fit in the chassis. Makes me think it may have come out of a truck. Out of curiosity, is your 390 oil pan a front sump or split front and back or?