Looking through the port you'll need a torch to see things, that mirror helps a lot more too
With the piston at BDC you can also see the opposite wall.
Anotehr way to check may be to take the head off, less work but the proper way is to remove the barrel. You own a two stroke now, part of the ownership is swearing as you take it apart.....again
Yes you should check the barrel. You're gambling on the potential cost of replating your cylinder just because you did not check your piston.
Anything that changes gas flow either on the intake or exhaust means you should as a minimum check your jetting.