300 MCA points is a decent loss but your GPA/test scores put you above the averages for the College of Architecture overall.
Average SLO GPA: 4.03 Average ACT: 30
There is no way to know how competitive the Construction Management Major has been but the SLO projections are 341 applicants for 100 spots. If they have a 33% expected yield for that major, it puts the acceptance rate around 88% which are great odds.
Best of luck.
You can also check out the Final status thread from last year to see if any Construction Managament MCA’s were posted.
http://talk.collegeconfidential.com/cal-poly-san-luis-obispo/2128373-cal-poly-slo-2019-final-status.html