New main caps or old

I would go with aluminum main caps.
The steel on steel in stroker apps puts a lot of stress on the main webs, and transfers it to lower cyls as well. The aluminum caps will "soften up the hit." alum caps flex, steel caps just snap. just my .02, am sure some that havnt seen broken steel caps or broken lower cylinders (esp on major thrust side) will dissagree. The new caps will need to be sized to the block.