I'd stay with the SunTour set up, myself. Nothing wrong with Shimano, I have an all 105 R500 I let my son ride now that I built up. I am partial to SunTour because I owned a set of the then new Superbe line's brakes. Put them on a sweet Raleigh to replace the Weinemann centerpulls (the only non campy parts) and fell in love with the strength and engineering details on them. Still like a lot of the SunTour parts for C&V bikes and they always worked flawlessly for me.
Bill
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Semper Fi, USMC, 1975-1977
I Can Do All Things Through Him, Who Gives Me Strength. Philippians 4:13