Extract substring, convert to from MST to CST time zone

[F_Quint]

following another example in this community, I got the extracting part, now I'm stuck on converting this substring to ISO8601 

can I nest another function within what I already have 

substring(body('Html_to_text'),add(lastIndexOf(body('Html_to_text'),'Proposed Start Time:'), 22),24)

[krootz · Accepted solution]

@F_Quint , your output needs to be the same as the first param below without the 'MST' 

convertTimeZone('11/18/2020 7:00AM','Mountain Standard Time','Central Standard Time','MM-dd-yyyy HH:mm')