When you said oil fill, I didn't realize that you were looking for the oil fill level tube or dipstick. If the motor is a pre-1980 motor, the dipstick is supposed to be on the driver's side of the block between cylinders #5 and #7. The block sticks out just a little farther than the head and there would be a hole that the tube is pressed in. If it is a 1980-1985, the dipstick is on the passenger side and the spot on the block is just in front of the starter and is down low, just above the top of the oil pan. If it is after 1985, it would have the one piece rear main seal and the dipstick tube would be on the passenger side. Sounds like somebody left it out and plugged the hole. They are different lengths and styles depending on the side of the block.
Perfconn is correct about the timing cover seal and balancer. I was thinking rear of the motor, sorry.
Another thing that can cause the leak around the front is if the timing chain and cover have been replaced and the improper rubber timing cover to oil pan seal was used. There are two different thickness rubber seals that can be placed in the timing cover, depending on which cover and pan is being used.