Buffing a firewall?

[Henry Rifle]

Looking for ideas on how to buff this firewall. I've color sanded it with 2000. That's all it took to get rid of the orange peel. However, there are so many sharp and raised edges, it's a recipe for burn-through. I'm used to buffing big, flat cars - like my 68 GTO, my 56 Olds and 52 Chevy (all gone . . . sniff).

I'm thinking about putting blue painters tape on all the sharp edges, buffing the major areas, then touching up the edges by hand. I sure don't want to do this whole area by hand. I'm too old for that.

Also, buffer speed with the first cut and a wool pad? 1200 - 1500 RPM?