I own a Gameworn Dynamo Jersey of Alex and it is a 58. But it was too big, so he changed to 56 after a couple of games. The same with Lecavalier, he started with 58 when he played for Kazan and changed to 56. Good for me, so I got my hands on his jersey as well.
Please note that there could be a difference in sizes between the russian producer Lutch and RBK, especially now with the slim design.
If you want try to email Barry Meisel at www.meigray.com he markets all the Game Worn jerseys for the Capitals and he should be able to let you know. He wore a 58 last year and with these new jerseys he may have went up in size.