Target And Source Columns DataType

I need to create an Bulk upload utility using ASP.Net and SQL Server. Below is the process for the uploads -

Excel Template wherein user will enter the details. A Tab-delimited output file will be generated using the VBA.
There are 2 tables - one is Temp Table which is replica of the the final table and second is the final table
Using File.OpenText(filePath).ReadLine() - All the Rows from the tab delimited data file will be inserted into DataTable.

using SQLBulkCopy the tab-delimited data file data will be inserted into the Temp Table.

Data will be validated based on the data inserted in the temp table. If the data as errors then the temp table will be cleared else the data will be inserted from the temp table to the final table.

My Issue is that in both the tables there is a column (Name : PeopleKey (Int PrimaryKey)). If the user enters Alphabetic value then the Bulk Utility is failing. Below are the two options in my mind -

1. I can change the DataType in Temp table from int to VARCHAR. So, the data can be inserted at first and then I can validate and get the data corrected. But i am not sure whether it is the right way to fix issue as the source and target tables columns are different.

2. When the data in inserted into the Datatable by following Step 3. So, once the data in inserted into DataTable then i can validate there. Thus the source and target tables Datatype will be same.