You got the idea. They actually started rating boats on a voluntary (but expensive) basis in the late 70's, then made it a law. My ex-Coast Guard buddy said he thinks it was '83, but it doesn't matter when it was exactly if yours was made in the mid 70's.
BTW you probably would care which way it floated, as your gear would be on the bottom and it's hard to stay on a capsized boat, especially if your knocked unconcious or wounded. I know, my dad learned the hard way that our 27' sailboat wasn't Exactly 100% self righting when fully loaded, 85 nauticle miles SW by W of Point Sur on a tack back up the coast from around Pismo to Moss Landing. We were on the way back up the coast after going from the South end of SF Bay, through the Golden Gate and down to Oxnard (we were headed for Baja but ran out of time).
Boat SAFE and always wear your PFD when under way. They can and do save lives.
Have you set up a drift anchor? I didn't see any 5 gallon buckets
on ropes. Your size boat would probably only need 1 or 2 buckets.
Make sure you tie the rope to holes through the buckets, not the wire handle that'll pull out in a 10Knot wind.

Tight lines,
Wade