High Torque Starter Recommendation?

I have a 69 with a 396 from an Impala. The engine is far from stock. Roller cam, and some other stuff. It's pretty stout. I didn't build it, so I don't know what's in there. Anyhow, the starter, which I speculate came with it, is having some trouble turnin' her over. It starts, but it's slow. Worse when it's hot (a GM classic...same prob with a GTO back in '70...).

Anybody have a recommendation for a higher torque starter?