Your machinist probably rolled his eyes but you insisted on a part or you just didn't know the little in and outs... You bust out the dremel or die grinder. Make sure you have the right bits to work on aluminum! Triple check clearances! And then have at it. Below is a Weiand Stealth I picked up from a memeber here. The hardware is ARP Stainless steel. The head is a reduced size & 3/8. The washers is wide. The idea here is to create a flat spot wide enough to allow the washer to sit flush on the intake. Some spots were like a quick touch up but the passenger side rear was a carving!