I have the exact same box with my pump mounted exactly like yours. You're right about the slanted sides, was definitely tricky getting it flush in there.
So, are you heating water to mash temp in your HLT, transferring to mash-tun then just keeping it even with your Heating Element?
So, are you heating water to mash temp in your HLT, transferring to mash-tun then just keeping it even with your Heating Element?