The C8R2203 recone kit is used to build a 124A/124H/2203A/2203H driver. That driver can be built from any 121A/121H/124A/124H/2202A/2202H/2203A/2203H/2204H core.
NEVER use a C8R2203 kit to build a 121A or 121H.
That would be wasting a great cone kit. The C8R2203 should only be used to build a 124A/124H/2203A/2203H. A 121A or 121H can be built with the C8R121A recone kit (still available) using any 121A/121H/124A/124H/2202A/2202H/2203A/2203H/2204H core. The C8R121A recone kit differs from the C8R2203 kit in two ways.
1. The C8R121A kit contains a "100 gram" mass ring (~ 95 grams) while the C8R2203 kit contains the usual 124/2203/136/2231/2235 "50 gram" mass ring (~ 35 grams).
2. The C8R121A kit has a much stiffer spider.
Cones, surrounds, and voice coils are the same.
The C8R2203 is NLA from JBL while the C8R121A kit is still available. I believe the C8R121A recone kit is ~ $172. The C8R2203 kit is not worth $300. Rarity means absolutely nothing to me. I would buy a brand new LE14H-3 before I would put $300 into a 124 or 2203 rebuild.