In rereading your reply, I'm not sure if there may be a misunderstanding. The actual property site is about 0.3 acres measuring roughly 130 ft by 115 ft. The building plot area of 40 ft by 60 ft is what I selected as a good area for excellent views and also where the topography map shows that...
Actually, I had the potential plot plan as 60 feet east to west and 40 feet north to south.
Changing the rectangular plot plan to 60 feet from north to south and 40 feet from east to west results in slopes as follows:
East to West on the North side: 45%
East to West on the South side: 67.5%...
I am considering buying about 0.3 acres of which, according to a previous survey, over 93% is > 40% slope. The property has a "killer" water view and is close to an 80 year old house I already own (also in a > 40% slope area). A 40 foot (North to South) by 60 foot (East to West) rectangular...