I took some great photos of my daughter with (bounced) flash. She didn't do more than blink at f/5.6-light (which gets you f/11 to f/16 on TMY2), let alone thrash around screaming. Would you be terrified to carry a baby past a window with sun coming through it? Because just one second in full sun is 800x more exposure than received from a bounced flash set to f/5.6.
I have some wonderful photos taken with my RZ and bounced or softbox flash from her first week, though mostly I used digital (for the high ISO, sensor stabilisation and 85mm f/1.4) and didn't bring the RZ into theatre.
Minimising light in order to minimise startling is a worthy goal so in answer to the OP, I will suggest TMY2 in Xtol 1+1 to get EI800 maybe EI1600; it will give you a clean 16x20" print from 6x7. The kid will probably sleep 80% of the time for the first couple days, so go ahead and make longer exposures on a tripod in that period. You can do good lighting of sleeping babies with a 40W bedside lamp...