I agree with the aluminum head suggestion. While some may argue that the cost to refurb the 915s "is not even close pal" you'll still end up with 40 year-old cast iron slugs. Slap on springs and keepers and the price does start to get closer to the Stealth head price. However, keep in mind that just about everyone is in agreement that the Stealth heads need a teardown prior to use just to check things over.

If your budget can handle the extra bucks, go the stealth route. Maybe just clean up the 915s and then sell them. The "not even close pal" guy would probably jump all over them !!