Probably best to leave NC-74 at 65 mph while it's still unconnected segments. Maybe when it's complete from US-52 Future I-74 to US-421 Former I-40B would it make sense to raise that connecting to freeways at both ends to 70 mph. Kind of an argument for 2023 though.
Once the Beltway is complete, the entire length of I-74 / Future I-74 from I-77 near Mt. Airy to I-73 near Asheboro should be posted at 70 mph.
And as I mentioned before, with the exception of through Greensboro, all of I-40 between Winston-Salem and Raleigh, all of I-73 between Asheboro and NC-68, again except through Greensboro, and US-421 southeast of Greensboro, should all be raised to 70 mph.
There's numerous segments of interstates and freeways around the state that still retain 65 mph and could adequately be increased to 70 mph. A system-wide study is warranted though NCDOT continues to raise them at a snail's pace one bite at a time.
I-85 around and south of Greensboro, I-40 west of Winston-Salem, I-73 / I-74 south of Asheboro, and US-29 / Future I-785 north of Greensboro are all currently posted at 70 mph.