I've never ordered a safari jacket through Luxire, so I would suggest contacting them directly to get started. Or maybe @CruzAzul would have some good tips since he's been very successfully in this endeavor with Luxire.
They might not nail everything 100% exact on the first go-round, but the sizing should be pretty spot on for the most part. Make sure to explicitly spell out specific details that you want to make sure your suit has. I would not recommend using a suit jacket as the pattern for a safari jacket or a denim jacket, chances are your measurements and then overall construction may be significantly different.
Wanted to double check on this and see if the #8 Alt Wiens were going to be re-ordered again anytime soon. There might be an order already out there that hasn't been fulfilled yet, so I'm guessing probably no new orders until that one is stocked.