300 lb. test should be plenty, assuming you're ~ 200 lbs. I haven't tested different ridgeline materials yet - I'm working with the stock HH ridge and haven't added a ridgeline to my Speer type yet - but I cut my HH ridge and added a small 'biner. The 'biner is rated to 300 lbs. and hasn't showed any signs of stretching at all, even though I generally hang my HH very tight and almost horizontal. Stands to reason, then, that 300 lb. test line should work fine.
"Physics is the only true science. All else is stamp collecting." - J. J. Thompson