ORIGINAL: BobCo19-65
I don't think that moving from 125 to 185 will increase FOC all that much. You may want to looking into steel adapters and glue on heads.
But, here is my main caution. Aluminums do not fly all that well with extreme FOC. Personally, I could not get my aluminums to fly that great past about a 150 grain head. Iasked the question to Dr. Ashby himself and he found the same results with aluminum. With carbon though, I was able to get 26% FOC and had great flight. I was using 190 grain glue ons, adapter and brass insert. I also had 5 grain per inch tubes which made a 720 grain arrow.
Just to add my experience, I have found the opposite. You have much more experience than I. But with my zipper bow, I had 265gr up front with carbon gold tips. But never could get the right combo. But I had fantastic results with 2216's and 200gr up front. But with my black widow longbow, I had the exact opposite of that. I found Gold tip 7595's with 315gr up front flies awesome, and can't find a aluminum combo to work as well.
I think the trick of it, is being able to find that sweet spot to clear the riser but keeping oscillation down to a minimal to keep the arrow from showing weak reactions. And aluminum, the window for that with shooting off the shelf is very small. Where carbons won't oscillate near as much and you have a much wider range of operation. But either case, finding the sweet spot. I could be wrong.