To properly locate the holes to be drilled in the crankcase, get a set of transfer punches. (Search for them if you don't know what they are.) Get the proper size numbered drill for the thread (IIRC, it is 1/4-28?). Get a high quality thread tap, and experiment on some blocks of aluminum if you aren't comfortable with tapping threads. Get a good aluminum tapping fluid, Tap Magic makes some.
Hold the mounting plate in position, and have an assistant transfer one hole, using the transfer punch, to the crankcase. You may need to space the plate away from the crankcase a small amount to get the transfer punch to be fully engaged with the mounting plate. Remove the stuff, and drill a small pilot hole, maybe a 3/32" hole or so, then drill the tap size. Tap this hole, and then mount the plate again on the engine using the one bolt. You may need to put spacers under it to allow the transfer punches to properly engage, and then transfer the remaining holes. Tap away and that part will be done.
Send the pulley thingy to Klaus, well worth the $50.