you can do the WP if you did the head !
There are lots of posts (do a search) on WP replacements.
You will need real slender flex socket in 13mm with 12" extension and 3" extension. Snap on FLX 13 1/4" slender extensions have been recommended but I was able to reach the back bolts on my 300E with a craftsman flex socket and 3/8" ext. The fan pulley will require a small tool to hold the pulley while you unbolt. You might search for the posts I put up about re-using the belt tensioner and getting the right tension on a used unit. (I assume you might be re-using tensioner since you implied that you had replaced some things on the front of the motor recently).
Check my posts and those of others, then go for it. Fastlane here has the pumps. Everything including thermostat and new belt ran me less than $200 when I did mine recently.