"I have a standard start date and a numeric time (in two separate fields)" — what are the variable names? Please don't make us assume we know which variables you are referring to, because we could get it wrong. Better, you should specifically tell us. Also, are these variables numeric or character according to PROC CONTENTS?
"... and a standard end date and numeric time (in two separate fields)" again we need the same information as above.
Your data doesn't vary except in the leftmost column REFERENCE_DATE. Maybe a more realistic example would be helpful. And also, we need data provided in a form we can use, which is WORKING SAS data step code (examples and instructions).
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