I run a girdle and steel caps with a short fill, engine has been together and raced 10 years, been freshened twice, all has looked ok, I went that route since it just didn't seem to be a good idea to have the aluminum caps with the old stock cast iron block. If I was rebuilding Id go the other way though I think. Ive seen enough of the stock block aluminum caps hold up that even though it didn't sound good to me back about 12 years ago when I started building that engine I'd go that route now, I would do a short fill though either way.