My block is done in four sections with Moroso epoxy. Three smaller, rectangular pieces cover the openings over the cam and on larger "T" shaped piece protects covers the opening in the front near the tower shaft bushing.

I was mostly mitigating the cam or oil pump drive from accidentally digesting a 7/16" pushrod and not too concerned with a small mesh size due to bushed roller lifters and non-needle bearing rockers. It would make sense to use a mesh smaller than your smallest part.

For a supplier check ebay. There was a guy selling smaller sections of stainless in any mesh size you can think much cheaper than the typical industrial supply shops.