The one on my bench is a 2782 but looks v. similar. Mine has a bumper movement cal 354 and dates from 1953, one of the first Constellations but doesn`t have a pie-pan dial.

Not sure whether the any bumper movement versions had pie-pan dials, but the one the OP's featured could be a later cal 500 which used the same case design with a snap-back.

I`m always wary of anything that pre-dates the cal 550/560 watches, parts are difficult to obtain and the movements aren't as robust, particularly the 500s. Bumpers are generally OK but broken parts are hard to source thesedays.

Dial condition is paramount when buying, and if the watch is gold capped or gold-filled the condition of the gold is v. important particularly around the lugs. Not sure about the original gold thickness, I`ve heard figures of 200 microns quoted, far better than gold plate which is usually 20 microns, but regardless of the original thickness it's the degree of wear that counts. A tiny bit of wear-through on the very tips of the lugs is acceptable but I`d avoid anything heavier.