Current Outer Orbit Questions

[spw4949]

I just got a 36" current outer orbit fixture for my 46 bowfront....It has 2x250 watt MH's, 4 39W T5's & 12 LED's, it's definately a sweet fixture. My dilema is I'm concerned that 2x250watt MH's will be too much light, right now I have a bunch of softies, zoas, rics/shrooms & LPS. My tank has been up & running for a year now & I have everything placed exactly where I want it. I do want to add some SPS(hence the upgrade) but I'm a little worried about frying what I already have and sending my electric bill through the roof considering I'll be doubling the wattage( I currently have a 6x39W Nove extreme pro). So my plan was to swap the 250's for 150's, it's an electronic ballast so I know I can use lower wattage bulbs with those ballasts. I was looking at 150W MH's online & the ends look different to me than the 250's...what exactly would I have to do in order to make 150's work? Are there 150's that will fit the endcaps that are in there or would those have to be replaced & how hard is that? Any help/advice would be appreciated.....