I've seen 2 #230 casting blocks 1 didn't have the huge main webbing and the 1 with the huge main webbing had a crack across #3 main saddle.
I have 3 #630 casting 73 400s, 1 is my 470, 1 has a cracked main saddle (mock up block) & the last 1 is in good shape but will need alot of detailing since it sat outside and will get 8 sleeves which I'm trying to track down a sleeve that will start slightly over the 4.342 standard bore.
I have a 383 Im going to experiment with also might see about getting 440 sleeves to fit, not sure if that's even possible but I'll find out