Very good effort and nice script !

Just to add my 2 cents,

It is not good to run the job every 2 mins (or any interval) on a highly busy prod server as it has its own overhead.

I had this type of job running and emailing the blocking details, but have switched to EVENT_Notification

which uses BLOCKED_PROCESS_REPORT. This is smart enough to fire when there is real blocking (and this can be adjusted using sp_configure). This can fire a sql agent job to insert the xml generated by BLOCKED_PROCESS_REPORT into a db table and if you want more fancy reports, you can email it by shredding the xml.