That's odd. The Apple Upgrade kit came with a new case front to accommodate the new chassis required for clearance.I had one when I was a child. It was an SE which was upgraded to the SE/30 using an Apple Upgrade kit. At some point, I took a pen and wrote /30 after the SE name on the front!I doubt I'd do that today.
Also until JuanJavier weighs in again with some answers, he may be talking about an actual SE 1/20 which came with 1 MB RAM and a 20 MB HD. I do believe that all of those models were IWM 800K only. Once they switched to 1.44MB I think they were marked only SEFD and Superdrive and the 1/20 was the standard configuration. That does not preclude a SWIM upgrade or a logicboard swap, the later models of the original SE had the revised chassis, so no need for the front case upgrade.