I want to build a large concrete breaker. The engine is picked out. The vibrator width can be decreased for thicker concrete and increased for thinner concrete.

I want to create a vibrator by turning an eccentric shaft with 30 hp at 2400 RPM using the entire horsepower to turn the vibrator. I will need to make the shaft in a machine shop. I will hold the shaft on each end with roller bearings. The weight of the total vibrator could be any weight (adding weight to the vibrated part as necessary). I need a vibration with an amplitude of about ¾ inch.
The shaft can be made from something like 4” solid shaft (mild steel) turned to 2” ends with an eccentric lobe in the middle. It can be 1 foot to 2 feet long if needed in the lobe area. The lobe length, weight, and distance from center are the numbers I am looking for.
The question really becomes how much eccentric weight at what distance from center can 30 hp turn?

... and what the bearings can support.