I have at least 2 later style 550 engines with complete top ends. However, neither of them is apart at this time, so will probably take me a week or so to investigate. I'm guessing here, but short of buying NOS cylinders from Paul Miller (if he even has any AND you were willing to pay his price) your chances of getting standard bore barrels are slim to zero. If I have a set of good .020 barrels you could buy the pistons/rings for them and be back in business. My 550A is the same colour as yours, only with ~3400 miles on the clock. The last owner of that poor Indy must have really abused it to wreck the engine like that. These bikes REALLY do not have enough power to (normally) hurt themselves. The guy must have run it low on injector oil OR really overrevved it. Those kinds of guys need a few lessons on how to treat machinery in general. Email me if you are interested in the barrels (assuming I have a good set) and we can work out a price.