No worries Ed, if you've got room in your basement/shop, an old oven is a handy tool for not only dropping sleeves, but also for curing engine paint, loosening valve guides, curing powder coating etc. I bought a small one on eBay for 2 bucks and used it until I scored an industrial oven which has much more room.
Be careful with the sanding, even with a wide block it's easy to "round" the gasket surfaces, that's why I use the strip disc, it's fast and only removes the old gasket, and not the aluminum. Don't bother with fine abrasive paper, all you'll do is polish the old gasket. Cheers, Terry.