"Giant in the Forest" by Frank Belknap Long

Published in Science Fiction Quarterly, 1955.

Gauguin: Eugène Henri Paul Gauguin, a 19th century French post-impressionist painter

Sounds like Long dreamed up Star Trek's transporters, with all their messy problems, a good decade before Roddenberry did... Also, the idea that basically all aliens are human or human-like...

6 foot 5 inches = 195.6 cm. That's a big boy!

300 feet: call it 100 meters, close enough for government work.

Whirlpool nebula - today called the Whirlpool galaxy, M51a, or NGC 5194. It was the first galaxy to be classified as a spiral galaxy.

Giants there were in those days: Genesis 6:4

The picture used is an illustration for the story in "Science Fiction Quarterly" by Will Hulsey