let me add my experience,I used to drag a 69 Chevelle 396 with a Muncie,never broke the tranny. back in the day,that's all ya had behind big block GM cars even guys running in the 11 second range which was quick then.The Saginaw 4 spd isn't as strong, but many guys ran them with modified smallblocks.
Like ya say,a no issue behind a 235.In fact Leo Santucci used to run an all out drag race 261 Chevy,buzzed it up to 7000 rpm.He told me the strongest non streetable 261 can't produce more than 290 HP and 350 ft lbs of torque,so no worrys for a Saginaw behind any 235/261.