Double Breasted Vest Where Can I Find A Vintage Style, "u-cut", Low Gorge, Tuxedo Vest?

Where can I find a vintage style, "u-cut", low gorge, tuxedo vest? - double breasted vest

Vest must be "U-Cut" on the front, which means that many shows in front of the T-shirt and not when the jacket is buttoned.

I would prefer that the vest can be achieved.

This style is popular in the 1960s, and it looks worn by Frank Sinatra.