Ok, I wanted to follow up. It doesn't really matter which tube you use if you can find one that fits into the hole in the engine block and can be clamped to the hold down (jury rig it if you have to). Get the dip stick that goes with the tube.
After you have installed the tube check the oil level. It probably will not be correct according to the marks on the stick. That is OK because you are checking for oil usage, not the amount of oil in the engine.
Then with the next oil change (after you have changed the filter and added the correct amount of oil, run it for say five minutes, shut it down and wait about 2 minutes. Now the check the oil level. Mark the stick (file a small V into the side of the stick for the full mark). Now look at the original marks on the stick original dipstick (if you have it, if not ask some one here to do it) and measure down the same amount from the V you cut and file another mark on the stick for a quart low.
Used to do this all the time on auto engines that were put into boats since they usually were set in there on an angle and the original dip stick markings would not read right.