I don't have any detail yet about DAC.
but, I know one definite thing.
Let suppose you have sin(x) ideal signal.
if this sin(x) signal pass "ADC-DAC", anyhow result will be same with sin(x) signal.
but, the problem is ADC and DAC is not ideal in real world.
because of resolution of ADC and DAC, and other factors,
resultant signal sin(x) will have some delay and some aliasing.
so, my meaning is... you don't need find a DAC block or function in simulink.
you can put some delay and aliasing(such as zero order hold (zoh)) to consist DAC.
but, which values you need to use -> its defend on what you want.
for a example, If your target is normal 8 bit DAC. than you can set up value of zoh as much 8 bit.
anyhow, you can make DAC by yourself simply. it's a not a big deal i think.
such DAC simulink in google. you can find more info.