How to mount this motor, so i can still tension the belt?

[daleyd]

Courier?

I'd chip in.

 

[Turbo]

Probably too late now but here's an idea. Place the motor so that it lines up with the existing mounting plate, allowing for room to cut slots for tensioning the belt. Then adjust the position of the pump to line up the pulleys & drill new holes for the pump. It will be easier to offset mount the pump as you don't have to worry about cutting slots.