The dimensions Healingbear gave you may work just fine in your application. However, the tube that the dipstick goes into may have been replaced or driven into the block deeper or shallower than standard and will not necessarily register the oil level correctly. The safer course of action is to drain your oil and add 5 quarts of fresh oil. Where the top of the oil sits is your full mark. You could also stop at 4 quarts and mark I quart down.
I am using a stock dipstick and adjusted the tube (a piece of brakeline) length to correctly measure the oil level according to the dipstick.
Chuck
