Interesting question. Unless you know and trust the guy offering you the Indy block I'd be skeptical. It is possible that there is something wrong with the block. Even if there isn't any wrong with the block there is the possibility that it might not work for you. For example, is the Indy block capable of internal oiling or will you need to run an external oil setup? Are the lifter galleries drilled for oil or not?

If the Indy block is the right one for your application then the only issue is if you want to deal with the slight extra hassle of running one on the street. The blocks grow a lot more with heat so bearing clearances have to be tight when cold. So you can't beat on the engine until the block is up to temp.