Iron B/RB Race Block Availability

Looking to build a RB stroker 512+ engine (close to 600" if I had the right block) for the street car that makes more than 775 HP. Besides the aluminum blocks by World, KB and Indy are there any iron blocks being made? I have a 68 440 block that I do not want to use because it appears that is not going to last long before the cylinder wall cracks (after using block sealer and main girdle). Am I missing something?


I have been out of the scene for 17 years and there seems to be everything available except a strong iron block. I do not want to use an aluminum block on the street. I have enough headaches. Yes, my 68 cuda has not been out of the garage for 17 years ( I cannot believe it either).

This site is great and I have learned a lot in the last 7 weeks. Any help suggestions regarding the block is appreciated.