It looks from the pictures that the tubes are not oversized: it gives a smooth ride. Oversized was the trend in the late 80s early 90s and made for quick reaction bikes but gave up smoothness and a hard to describe feeling, as in being one w the bike.
slr is some kind of progressive cam inside the lever. It boosts leverage/ travel of the brakes as you press the levers. Normal levers like suntour otoh, gives more feedback but less brute force.
M733 levers are tanks and have great ergonomics. They weigh like tanks as well.
I would run a shorter 15 degr. rise syncros stem. Those bikes were usually built that way to deal w/ the steep terrain of west Canada. A tall hbar and a shorter saddle to bar distance gives you a good control and fast reactions.
93 is m737 vintage. Light, compact gearing, slr breaking, pretty and half the cost of M900 xtr Judy SLs are nice but so is a mag21 tuned w/ travel extension. I had both and prefer the mag21 BUT... finding seals/ parts for mags is not easy.