I ran into this problem w/ my 200 6.. I have a $80 set of springs and retainers I can't use. nobody had the 5/16 tool and were going to make me buy it if I was going to have them done... I ended up doing a little experimenting and used 302 ford intake springs w/ 302 2 pc intake retainers, w / 200 ford I6 centers.

the 3/8" or 11/32" cutters are very common tho. I'd be certin there a dozen places in Auburn that can do them