You should definitely hone the block before changing your rings- after almost 300k miles, you're not going to have any honing marks left on the sleeve to help wear in and lubricate your new rings.
Have a shop do it- going in with a hand drill and a honing bit won't really be that great for trying to maintain a specific honing angle.
8-10 psi on a good size turbo will be perfectly fine on the stock compression and stock pistons. Just get it all tuned properly and you'll be fine. If you want to go with aftermarket forged rods and pistons, you can get those pretty easily too. Just make sure you know exactly what size pistons you need- your block may require a slight bore to clean it up.