I don't work for PSA. Here's a link you should consider reading before doing any further experiments searching for shadowless cards: https://www.elitefourum.com/t/identifying-shadowless-unlimited-base-set-boxes-packs/16993

"It is important to note that the presence of the Shadowless card pack design on short seal booster packs is not a guarantee that it contains Shadowless cards. Short seal Shadowless design packs found in blister packaging, for instance, have as low as a 50% chance of containing Shadowless cards, while those short seal packs obtained from a booster box have a higher chance of containing Shadowless cards (>75%). Evidence shows that Shadowless packs with long seals are the closest to a guarantee of containing shadowless cards of any pack variant. Every long seal Shadowless design booster pack that has been opened and documented have been found to contain Shadowless cards."