In over head cam engines, the cam follower…nicknamed a bucket…fits around the valve spring and acts upon the valve directly.
Now, in high performance pushrod engines
and ohc applications which employ a cantilever/rocker valve actuator
a roller is employed to follow a fat cam lobe a regular flat tappet couldn’t handle.
Is it possible/available to have a roller bucket?
Sure. The term of art in machine design is “roller cam follower.”
The only real drawback I can think of in an OHC engine is that it increases the height of the head by a fair bit—maybe 1.1 times the diameter of the roller follower.
Image searching “roller cam follower” yields components less at home in an engine and more in a dishwasher.
Indeed, adding a roller to a standard “bucket” would double the length of a cam follower.
Taller roller buckets requiring a relocated cam held in place by taller camshaft brackets, taller valve covers, and longer chains/belts.
Ideally, the upgrade could take place with the engine in the car instead of disassembled on a bench
I figure, give new life to the OHC diesels available from the late 70s to early 90s.
Respectfully, so what?
You asked if it was possible, and I answered your question. I gave you the generic name for the component in question and mentioned an obvious drawback. What kind of answer were you expecting?