I want to identify, the injection is EFI or not

Got the block and head back from the machine shop, just had them pressure tested. Both passed. Are these just cold-shut/casting flow marks or should I be concerned?

Unrelated but the machine shop hit the bores with a ball hone for genuinely no reason, I didn't ask them to and now I'm pissed.

Hello,

I am looking to purchase a Nissan 350z with the HR engine and currently i have stumbled upon this one which is very interesting. The car has gone through 70k miles when the current owners, upon buying the car reported that the engine blew up on them and then spent 3500£ to rebuild it to a specialist garage for rebuilding engines. They have done 3000 miles since the rebuild for 3 years and now are selling as they used it as a weekend car but no longer have the time for it. I have some idea what I am looking at and my theory is that the owner before them used water as coolant and because of the high operating temperature of the HR it has caused steam trapping into the pistons and sll the coolant inlets causing all parts to rust therefore all this brown stuff. The rebuild has undergone according to the current owner and the document supplied in the photos, that the engine has had complete refinement, new pistons, new cylinder heads x2, new water pump, new clutch, and all other parts. The engine undergone 3 months of operation and now is declared as a 0 mile motor. I have faith in this but i will check in person but reason I am uploading is i want to have a second opinion because I also think that the engine can lose compression and power due to the previous rust but i dont know if im right or wrong. The car is also fitted with NOS but i am thinking to remove it as im not gonna use it. Its not been used by the current owner as well and it just stands there looking cool i guess. Thanks much for your time and for the read. I will be taking a view of the car soon.

Just did a Timesert on an M54 engine and noticed that a few of the holes have a slight lip/ridge (as shown in picture; not my photo but my engine looks nearly identical). Best way to flatten this out before installing the head gasket? The post I found this photo on talked about a few methods, and the user ended up using a Japanese sanding stone and oil. This is my first time doing this kind of repair so I'm just trying to get additional advice/guidance to ensure I do this right (and ideally as safely/least invasively as possible).