Here's a picture of my cage that I recently re-did. It's hard to see but on the far right side there is a ramp which leads to another grid(that has been zip tied to the cage) covered with coroplast and then another ramp leads to the 2nd floor. I did this because it took up less floor space and made the ramps less steep. If I were you I would have a ramp at the bottom either from the house going down or use a grid like I did. 8 inches could be quite a ways to jump down especially if you get young pigs. Pigs can jump, no doubt but when they are running at full piggy speed there is a possibility that they could jump off too fast and get hurt.
Good luck with the cage building and search for pigs. If you need help finding pigs let us know what area you are in and I am sure people will be more than happy to help!