...Spacer the Pulleys? Perhaps.
Here's what to do:
Remove the Bolt that is in the way, 'Spot-Face' the Boss, Down with a Piloted Counterbore. Because this is a 'Piloted' Counterbore, You can Machine it with the WP still mounted and in the Car. Use a 1/2" Hand-Held Drill MOTOR. Mill the Boss, Down to Achieve clearance, being careful Not to break through the Jacket!
Next, CounterSINK, the Bore, deep enough to seat a New Bolt. Install a Grade 8 'Countersunk-Flathead' Allen Head Bolt of the Proper Dia., Thread and (decreased) length. Be Very careful if You go this route, as Tightening the CounterSINK Bolt TAPER, can split the Aluminum.
OR, You can, perhaps, spot face deep enough to use the same Hex Bolt.
Job Done!
MJ
P.S. Yes! You can Re-Machine From 3 to 4 Holes. You'll need a Rotary Table or an Indexer, Center with a Dial Indicator, find the Exact Bolt Circle, A go to town with the proper size drill bit... every 90 Degrees. The Experienced will First Center-Drill the Position Before Drilling. This Helps Prevent the Drill Bit from Walking off-Center. "When the Bore Starts Straight, It will End Straight!"
Keep it Balanced by NOT Using Any One of the Existing Holes, I.E. You will end with 7 Holes!!
This will be My last Reply on this matter.