What are you going to do with a 5/8's spacer? The spacers in Sky's kit are 1.268" and they have to be held to a pretty tight tolerance.
I tell you what, get a working drawing and take it to a machine shop. See what they will charge you to supply the material and cut them. Then go price the hardware to mount them up. Please post the results. Unless you have someone that will cut them for you expect to pay at least $100.00 an hour if not more at a machine shop. Do not forget you also have to factor in a profit, packageing, warehousing, if he is cutting them in-house machines and consumables, insurance for the shop, and employee costs.
There's places on Ebay that will do custom spacers for $75/ axle. I've used them on race cars, and they work quite well, so the quality is there.
