Why is there a hole in thye engine block between the fuel pump and distributor?

this is a 83 f100 4.9L6. I thought that might be the purpose for the hole as well. How would you suggest plugging the hole? What can I use that will withstand the engine temp.

Thanks for your help. My dipstick is actually toward the rear of the engine. After the 1st reply I assumed the hole was there so the dipstick could be in either location. I plugged the hole and solved my oil leak problem.