NHC 250 cylinder inspection without removing head?

[LCA078]

I couldn't find anything in the forum about how to inspect the cylinder liners and piston heads without removing the head. Can you drop on borescope through the injector port? I think you need to remove a cup underneath the injector to drop through, but even then I'm not sure what is the opening/clearance to get a 0.250" borescope through it. #18 is the 'sleeve, cooling, fuel' that i'm referring to as the cup

 

[simp5782]

Its not that big. Maybe a corn kernel. Takes 45mins to set the timing mark on the accessory drive and pull all 3 heads. Hardest part is removing the fuel crossover screws

 

[LCA078]

Re:45 mins— This will be my first time so I expect an all morning job. I need to replace a broken cam follower so probably just remove that one head to inspect the innards while I have the top rack off. I’m assuming I have to replace all the gaskets, right?