rear main oil leak

my builder found the correct rear main seal, charged me $850 to replace last one that was the wrong one sent to him by Rapido Marine. If its gonna cost that much again I'm going to try it myself. Thought that was really high due to the fact that they just put the engine together and runs fine other than the seal leaking. I have been studying on how to do it. If anybody has any video's on replacing seal would be appreciated.

The easy way I use to pull the Ford one piece seal out of the block is to take a 5/8 inch long self tapping screw, the pointed kind not the ones with a drill head on the face.
Drill close to the outer edge of the seal but make dang sure you do not touch the block surface with the screw.   I use a battery powered drill to install the self tapping screw into the old seal.   Leave the screw about 1/8 inch loose. Take a flat bar Nail puller and use the end of it to slowly and carefully pull the seal out of the block. Sometimes I have to put three screws in and work all the sides to get it out. Sometimes they come right out with one screw.
Before pulling the seal or installing the screw look really hard at the seal and surrounding surfaces for your leak.   Make dang sure your leak is not coming down from above the seal.   Tap the new seal in with a flat surface. I use a piece of 1/4 inch steel 2 inch wide by 4 inch long.   You have to work around the edges of the seal on install and tap it in till flush all around.   It must be flush and straight in the bore to work.
$850. please sing me up also, Could do 4 of these in a day and I am old. I hope you are running again soon. consider adding a Speedi Sleeve to make sure your crank surface will work.