I'm pretty sure yes, but note the 899 uses 18 (or 19?) mm diameter master cylinder so it may not work well with these calipers. See other thread on 1199 brake upgrade that talks about 19 and 17 mm masters.
They won't work unless you get new brake lines and I believe a different master cylinder. I'm also unsure if the ABS pump from the 899 works with the m50s, but you fould always do an abs delete if it is a track bike.