Well...I am about to get my learn on. If I attempt honing first and order a new standard size piston and rings how do I go about testing? Is the only way to re assemble and do a compression test? Do i need to have the carbs/exhaust attached? Or can I just install the piston block and cover and crank the engine?
From the pics they don't look to bad. Old rule of thumb is if you can catch your fingernail in any given groove it's not going to hone out.
That being said, as Rods stated I can't tell if that's a sleeved cyl or plated. If it's sleeved it could always be bored. To tell if it's sleeved, clean the sealing area of the bore and look for a steal/aluminum parting line.
I would say your best bet unless you have all the inside mics to measure the bore after honing would be a cyl exchange top end kit. WSM performance has one at $635 complete. Gaskets, pistons, everything to put it back together. To properly hone it out you'll need to be able to measure the bore to make sure a STD size piston will fit without excessive clearance witch is critical to make it last any length of time.
If it's a plated bore and any scratches go through the plating it would need a sleeve or be replated. All of witch would be more than the kit.
Yes the exhaust will have to come off to hone. You don't won't the honing grit to get in the exhaust. When you hone the jug assembly will have to be thoroughly cleaned after. Before reassembly.
Personally I wouldn't do only one cyl and leave the others. But a lot would depend on motor age and condition.
I would also consider rebuilding the carbs while doing motor. This will make sure there not contributing to the lean condition.