Fred,
I've been knee deep into Cleveland research since I bought my car with a Cleveland in it. Drop me an email and we'll talk. Right now 408 is about the limit due to thin cylinder walls, excessive rod angles and the connecting rod pin intruding into the ring land area. However, there's a brand new Cleveland block that's going to be introduced shortly that is allegedly going to allow overbores up into the 460 cu. in. area. The biggest limitation on making the Cleveland larger is that the overbore is only .030 max. Lots more will be available with this new block. It'll be available in cast iron and aluminum as well. Aluminum will come first. It's a great engine, sort of a small block with big block canted valve heads. With the new aluminum head technology out of Australia, the old Cleveland bugaboo of all top end power and nothing at low revs is long gone. 600+ Horsepower and a table flat torque curve is common and cheap, available with a cash outlay of as little as $8K, all at only 408 cu. in.
