ATI's are typically always a press fit, even when heated they will typically not be a slip fit. I think it explicitly says in the instructions to not do this, but most people lightly sand the ID, biasing material removal slightly at the starting side, to make the interference fit less aggressive. I did this on an engine that has ~4 years of race use on it and it's still fine. I originally started installing it out of the box and it was going on fine but it seemed tighter than I'd like, to where I'd be struggling to ever remove it. Heat, grease, add an alignment mark, and install it with hand tools. As your tightening down the damper to install, it doesn't require a lot of torque on the bolt to get it moving. If you miss the keyway, the good news is you would likely feel it. I've never missed the keyway but I'd imagine you'd feel it with how little torque I had to apply to drive down the balancer. I also filed a small chamfer into the leading edge of the keyway on the balancer, which might have helped as well. I've yet to remove an ATI damper, just install, but I've heard removing them after they've been in service for several years is a PITA.
