I have no idea of whether you should shoot for the 1050 on your 125 - what are the dimensions, 4 feet long or 5?
On the 4 foot long Percula 120 which AquaMedic sell they go with 2* 250 watts. I am not personally convinced you need mroe than 3 MH bulbs over 5 feet. 5 bulbs in 72 inches is a lot of power for sure, but is a lot of electricity. There are other technical hitches too - you won't be keeping that lot on for many hours in total.
You need to be aware that if you are really going to jam in the lighting, beyond a point these fixtures cross, you will be needing tothink about coral physiology to determing how long, when you need the bulbs on. Overlighting a coral continuously can give it some pretty serious physiological problems