i have heard from alot of places that chevy will be bumping up the power of the zr1 from 638 to 755

 

I doubt that's going to happen.

 

I haven't heard that anywhere. I doubt it will happen. Most likely, if you "heard" that somewhere, it was a posting like yours on another forum: someone posts a message saying I heard or I think, someone else repeats it somewhere else and pretty soon everyone has heard and believes it.
Reasons an upgrade to 755 HP are unlikely:
1) GM does not have to do anything right now. The ZR1 beats everything in track stats, etc.
2) GM has a long history of making incremental, not large changes in power, around 5% to 8% additions typically in any model. If I had to guess I would say in a year or two, if they even bring out a revised version, they might go to 665 or 675 by using dynamic overboosting for 10 seconds, etc. (like the option on Porsche's new Turbo) - this would be cheap to do and get them an advertiseable increase. If they re-engineer the motor, I would guess they would go to somewhere around 695 to maybe just over 700.
3) 700 HP is probably about the limit of a boosted LSX engine with the required durability and emissions control, unless they go to an iron block (too heavy, not acceptable to the market) or significant re-gineering costs neither of which GM will do.
4) My guess is that GM will do nothing, then drop the ZR1 in a few years a bit before they gain even bigger glory by bringing out the C7. This is their track record: they did that with the DOHC C4 ZR1, etc.
5) What the 'vette needs is not more power, but to get modern: four wheel drive and a dual clutch EST manual transmission. A 755 HP ZR1 would not be that much faster on a road course or in a drag race. But a C7 with a slightly heated up ZO6 engine (550 HP) with those two features would very like just kill a ZR1 in either a drag or around, say, the Nurburgring.