not sure what stretch you are talking about as there are four to five stretches on the Rio Chama, but a few years back we did the Day Run from the Rio Gallina down to Abiquiu at about 300 cfs in IK's and hardshells. it was bony in a couple of spots but went surprisingly ok. I think 250 is fine as long as you dont mind scraping once in a while. If you want more action than floating, i would suggest lapping the Skull Bridge to just below Big Eddy a couple of times. Some nice rapids and it is easy shuttle.
Also dont miss the Chavez Canyon hike if you've got time, river left just after the christ of the desert. Leads up to a really short narrows/slotty-type section only 30 minutes or so above the road.
"Don't f$&@ing eddy out, just run it! Whaddya doin??" -LMyers