I have a 46-48 block at the machine shop. I had it hot tanked and checked for cracks. There is a couple small cracks from studs to water jackets, and one very small incomplete crack from a cylinder heading towards the valve seat. The block has 8 sleeves in it. The shop said that it was probably sleeved because of the crack. The shop says that it is a good block and the small crack doesn't matter because of the sleeve. Should I use this block? Does anyone that has built flatheads disagree with the Machine Shop that I am using? Thanks.