[GoreMaker]

I'm planning to build up my 1977's W72 400 for some extra power, without going to any extremes. The 557 block used in that year has a lot of missing material from the casting, but this is an original matching numbers block and I really want to retain it. My power goals are around the 400hp mark without any stroking, which seems to be near the upper limit of what these blocks can handle reliably for years and years. So keeping this in mind, I was wondering if it's possible to stiffen up the webbing a bit to reduce the chances of cracking.

Would 4 bolt mains help to stiffen up that area? Are the bosses present in the casting to accommodate 4 bolt mains without removing too much material?

What about short-filling the block, is that something that might help?

Are there any main girdles available for this application? Would that help to stiffen up the bottom end?