Shot peening engine block question

[SS427]

The engine out of our Yenko is just too crusty with surface rust and 50 year old paint that thermal cleaning will not do it justice. Our local machine shop (Tim Wilkerson FC owner/driver) owns the shop. Their tech suggested I use their Ampro shot peening machine to clean the engine. I will admit that all the blocks they had in house looked great though none were Chevy blocks. I was concerned about loosing the stamps of the front pad as well as broach marks though they insisted this would not be an issue. The pad on this engine is not in the best of shape and I would like to try and bring it back best I can. Before I make a $20k error has anyone here used this or a similar system to clean their blocks and what were your pros and cons. It has also been suggested that I make a steel bracket that protects the pad area so I will likely be doing that anyway but before I ruin anything I wanted to check. From all that I have talked to there is no issues with cylinders, bearing saddles or anything such as those areas.