I would go with Indy over KB unless it was a blower,turbo or a Big 3-4 stage NOS engine.And Bog George just said they were on their 3rd season with a Indy blower motor.Not saying KB is not as good as Indy,they are a heavier duty block and possibly stronger but Daymn near as heavy as a steel block.If I gonna spend the $$$ for a after market block,an aluminum block is well worth the $$$ over a steel block,but not in my opinion if its as heavy as a steel block.

PS Just so their is NO MISUNDERSTANDING I am not saying Indy is better than KB,just maybe better for what the OP needs because it is lighter.On a Race-Car we need to keep things as light as possible.