Some serious heavy hitter brass drums in this thread right out of the gates! Here's a couple of mine.
Ludwig 1920's NOB 6.5x14 8 lug
Gretsch Bell Brass 6.5x14"
Have you considered trying the Inde version of this? I haven't used the one that replaces a lug but have had good success with the one that uses existing holes from a previous mount (BR2). In my experience the BR2 was pretty dang close resonance-wise to using a RIMS mount and was miles ahead...
Is this trade with a friend? I'm wondering if you could do a one week or one month trial after which either party can back out no questions asked. Short of that, I'd set them up next to each other and play them and see if you like the Yamahas better.
p.s. Personally I'd pick the Yamahas.
There's lots of great info in this thread. Also this dating guide.
It's confusing because serial #'s starting with an L could be 1975 or 1985 but I agree with everyone above that given the power depths and the finish yours are from 1985. There are others here that know tons about these...
I've gotta stay active or I feel gross. Walking, bike commuting, golf (walking), yoga, and swinging a kettlebell are my main sources of activity these days.
I bought my Black Beauty in 2013 and that was right after they had switched the badge style from the one on the drum in the OP's question to the new style that's still used now and looks more like the 60's keystone badge. So given that plus the gasket data point I think we've narrowed the year...
Another vote for new even though I haven't even played the new ones. So this is based off of what others said above and elsewhere about the bass drum but also the build quality of my Live Customs at the same factory are top notch.