I can't tell you the length but you can figure it out on your own.
Change the oil but leave it 1 quart short of the published capacity for that engine. Run the engine for a few seconds to fill the filter, then take a measurement with a piece of semi-rigid material (like a piece of AWG 14 Romex).
Then, add the last quart and measure again.
It will be great fun...invite the neighbors, tell the kids! Good luck!
On their death bed, nobody ever said, "Gee I wish I'd spent more time at work!"
'68 Sprite 1275
'76 Midget 1500