I recently converted my van over to 5x114.3, I did it both for better brakes and for the future addition of an awful axle for lowering. My buddy had given me a set of wheels and slicks to use but found out that the vans have quite an odd setup. The center bore is 71.5mm witch matches Jeeps but has 12mm studs. The wheels I got ere 67mm bore so I had to make some modifications.
First I found some wheel spacers that had a bore greater than or equal to what I needed, 73mm in this case. With the spacer bolted to the wheel I used a router and a jig tracing bit to follow the inside of the spacer. Since router bits are carbide they cut aluminum with ease as long as you keep steady and take it slow.