So gave Kleen-Strip a try on my red liner. I just did a small section of the underside of my drum's lid for a test run.
Gave it 15 minutes and tried scraping. I got a good amount around the edges, but the middle hardly had a dent in it.
I gave it a second coat and really let it soak in. More red came off, but far from the results on paint.
That's after 2 coats and scrapings, about 45 minutes total exposure time.
So my guess is that with more effort and many more coats, it could get the drum to bare metal. But at 8 bucks a can or so, I think I'd rather just haul the thing to the sand blaster. Next build I will *definitely* put the effort into finding a tan liner or bare drum. Will probably use up the rest of the can I bought to get as much of the outer paint off and maybe save myself a few bucks on the sandblasting.