Nice find!
I have owned a 6"security six for the last 20 years and I love it.
They are very strong well built guns. It is the handgun I am most accurate with, and being big and heavy the recoil is managable.
I have been watching prices and these have been going up lately, doubling what I paid for it.
Mine came with Pachmyr grips, and recently I found some close out oversized wood grips on the Ruger website for $10. here is a pic.
Greg58