Never mind, I think the chords above are closer than I thought, but in a key too high for me to sing comfortably. Here's what I figured out for the key of A:
F#m A
Come all ye young fellows that's bound after sperm
E7
Come all ye young fellows that's rounded the horn
A E7
Our captain has told us and I hope it'll prove true
A E7 A
There's plenty of sperm whale on the coast of Peru