The stock old-school 1960s starters are junk, and need to go over the hedge. They are heavy and not all that powerful.
Modern, lightweight starters work much better, are resistant to engine heat and are smaller and lighter. There are numerous options available; some are high-torque models, others use a gear reduction system. The latter are typically more expensive.
I paid top dollar for a high-torque starter from Pantera Performance Center; it cost about $150 with shipping. It works great, except the starter solenoid mounted on the starter body cracked (could have been installer error, DOH!) and eventually it quit working. Dennis Quella sent me a replacement solenoid for free. Haven't installed it yet...
When I still had the stock starter on my car, I bought an almost identical unit to Dennis Quella's purchased from a neighborhood starter shop for about $100. Before I got a chance to install it on my car, somebody desperately needed it and I passed it on to him. That was years ago and it has been working fine ever since. When I went to replace the one I sold off, the shop had closed down, and I took the easy way out and just phoned PPC.
I've been hearing about these super-low-buck E-bay starters (referenced above) for the past month or two, and numerous people have bought them, although I haven't heard any results yet. I'm a bit skeptical of anything that cheap, but I suppose they could be just as good as the more expensive, traditional options?
If you're made of money, a Tilton-type gear reduction starter will do the job, for $400 or so?