On my moroso pan I used the oil dipstick in the pan and sealed the block. For my 302 I took a 1/8 in pipe tap and just threaded the old dipstick hole in the block. I did not have to drill the hole bigger. Then I inserted a 1/8 inch threaded plug and covered it with black rtv. Works great for 55 miles.
the classic guys normally pick up a wooden dowel and tap it into place, when going to a late model block(since the dip stick is in the timing cover) and drive it in the hole with no problems the oil and heat make it swell and seal perfectly