[eschaider]

Main stud girdles cost way more in time and money (maybe they are the same) than they are worth.

Cross-bolting a block that was not cast with the bosses for cross bolting is another cosmetic feel-good event. It will not produce the effect you are hoping for. Additionally, it will require replacing your existing main caps with main caps that have enough meat to cross-bolt. That usually means several hundred dollars for caps, and then don't forget, you will need to align bore the block.

If a side-bolted block was what you wanted for your finished engine, it would have been to your advantage to start with a casting produced as a side-bolted piece. If you ignore the cosmetic enhancement that adding side bolts to a non-side bolted block provides, you have not increased the strength of the assembly at all. It is possible you could have decreased the strength of the finished assembly.

Don't waste your time or money putting side bolts on a non-side bolt block. If side bolts are important to you, get a side-bolted block to start with.