do a google search or ask around for a machine shop/ fab shop/ custom place.
put the intake manifold on your valve cover and measure how much room you have between the end of the IM flange (on the stock one) to your PS res.
transfer that measurement to the cossie/knockoff and make a line.
tell the fab shop to cut the extra off and weld a flat piece on there
easy as pie and when i had it done it cost me $60. im sure you could find someone to do it cheaper or even take measurements if you arent confident. Just find a fabricator
Mine turned out like this: