My 340 bare block

In the top picture of post 2 is that not a crusty copper tube I see breaking thought the lifter bores? Or is it just some crusty crap in the gallery?

If there is no tube in there I have no idea what they were doing.

If you are going to do any oil mods, spend you time and money on the inlet side of the pump. Unless you are turning 8K plus, that stuff after the pump is just busy work.

Work on the inlet side of the pump. That’s were the restriction is, and it’s the best bang for your buck.
I would like to think of a shift point 65 to 6800 and maybe still pull into 7200 but 8K not likely. I don't know how far I can go and still be streetable to some degree I'm sure that's a matter of willingness to put up with some Bad Manners. I'm looking to something like track days on the closed road course. Autocross, Road Rally time-speed-distance type stuff. Autocross is really small for the Dodge Dart. At least the ones I've been to. The course is Honda size the cones are Honda size. It was a Stone Grocery getter when I got it .7 1/4 rear open differential. Very embarrassing at the autocross but I had a blast anyhow. Time progressed and their Came the 8 3/4 lsd a very healthy 727 new drive shaft add a leaf spring to the back urethane bushings . Stock sway bar in the front adapted. That grouping was a huge Improvement. all still with the 273 2 Barrel single-plane intake, huge performance. 273 has had nothing but basic maintenance oil changes points and plugs.