Needle bearings require the use of hardened inner/outer races to ride in, which typically are not included with a standard needle bearing. If you use a caged needle bearing, the outer race or case is part of the bearing and is pressed in as a unit. You’d then either run it on a hardened pivot/shaft, or have a hardened sleeve pressed over the pivot/shaft.
These inner/outer races can make a bearing appear bigger than it actually is.
The Nedellas’ incorporate a thrust bearing into the roller setup to take up the thrust load associated with bell cranks not mounted in perfect plane with the pushrod. If the setup you’re working with has the rockers in plane, the needle thrusts are not required but still make a huge difference in suspension movement under sever load. Cheaper setups use shims and/or machined surfaces to take up rocker slack which is fine for awhile, but they wear and gain slop which leads to sever bind and choppy suspension.