360 balancer seal
If it fits into the 273 cover with a slight interference fit like it's supposed to, and also fits the balancer....I see no reason it wouldn't work. It does go in from the inside, so it will be hard to change later on down the road. There are later model LA timing covers that the seal mounts from the outside, but using one would probably defeat the look of the 273 cover you have. I would be tempted to buy a new harmonic balancer to go in with it to prevent a leak if the seal hits the wear groove in the old balancer. You could use a Speedy sleeve on your old balancer, but those things are a ***** to install correctly.