Absolutely Brandons and Chataqua are hands down way better than the QRC. I have some from QRC as that was the widely available gears at the time I built my 450. I got some 428 gears from Brandon and they were great. My brother just put a Cr250 together and had the Chataqua gears and they are very high quality gears, hard anodized and everything.
13.5 should make it an interesting engine. I'd be afraid of gearing, a road bike is probably going to be geared more for the big end. So you'll end up in like 4 maybe, not sure. But, I'd shoot for 1:1 in the trans first and go from there.
Like Phiddy I have 13-15 and never change front drivers. From and 1/8 to 1/4 I ran the same gear. 24-26 rear gears and I might change 1-2 teeth occasionally depending on how well the track is biting. Since the 520 gears change roughly 3-400 Rpm per tooth. For you, with the 250 I know you won't be able to pull the gearing I am, but the 14 sounds close.