Frank, If you have sufficient clearance between PUMP pulley and the WP housing, rather than make/fit a shim or spacer to the crank pulley, remove the water pump and its back cover plate, and using a press push the WP pulley flange on to the shaft by the reqd amount. ------- NB. When doing this use a short piece of round steel stock in the impellor bore so that you are supporting/pressing directly on the shaft of the WP bearing- not the impellor or housing.----- There is usually enough room between flange & front of bearing to allow this, also be aware that some WP shafts have a reduced dia immediately in front of the flange that acts as a spigot for the WP pulley, if this is the case you may need to make allowance for this by counter boring the pulley slightly also.