pushrods with or without oiling hole?

You won't notice much difference in oil pressure with the oiling type push rod verses solid end ( non oiling ) . I agree with one of the above posts that you should seek the lightest ( and strongest ) push rod . Once they are oil filled they are heavier than one without the oil hole because the cam is now lifting the weight of the oil . If you are building for street use it won't make that much difference but if you are building for a class you need every trick known. Use a GOOD , name brand synthetic oil and you won't have any lubrication problems . If you have had any head modifications performed i e .
milled , you should purchase a measuring push rod ( Comp - Cams ) and purchase the correct length for that engine & cam configuration .
Have fun with your build .