Why bother? Thats the real question to me. If that gun was in high condition with 30 barrels what would it be worth? $3500, 4,000? If you bought that gun for $1100.00, then sent it out for sleeving for 1500-2000 and then pay to have it shipped to you for 400-450 you are going to have 3,000-3550 in it. Add in a freshening up of the stock for another 100-200 and you just paid full price for a sleeved gun. Worse as other pointed out that gun was retailed by them but most likely brought in in the white if not even more finished.
You can get sleeving done for different prices and my 1,500-2000 might be on the low end for what you want. A invisible sleeve job may be more. Im sure if you lived in GB and had friends in the trade you could shop around. We dont. And I cant count the number of auction guns which I liked, that seem to go for 150-250% of estimate. Either keep it as is or dont buy it.