Winner!

Couple close guesses but 1959 383 RB is the most correct!

The RB 383 engine was the very first 383 cubic inch Chrysler engine ever offered, as well as the first raised deck big block wedge engine. The same engine was also offered in 1960.

The 1959 Chrysler 383 2BBL engine was the base engine in a 1959 Chrysler, it was rated at 305HP, the 383 RB 4 Barrel, rated at 325HP, was optional. The same engines were available in the Desoto Adventurer which offered a 350HP dual 4 barrel version. Dodge had 383 RB's as well, thier 4 barrel version was rated at 320HP.

Here's a restored 59 2 barrel version in a Chrysler Windsor