...if you're going to build a boosted motor and you're upgrading the "arm" from say a nodular unit to forged, you may as well go bigger even if it's nominally bigger.
Maybe counter intuitive for some (even me), when I built my blown FE project I went with a nitrided 1U 428 crank even though I had a RPM forged 4.250 unit on the junk pile. I've never hurt a 428 crank and figured it'd work well for me, which it has. I'll use my RPM "arm" if I buy an aftermarket block...and might do some "real" drag racing.
The 2.5 crank in a Turbo 2.3 is a wonderment to me as well. It isn't a direct bolt in for an earlier 2.3 block and the fiddle'n 'round is not worth the effort especially when the bottom end of a 2.3 Ford is as strong as an anvil (just as heavy too). Been mess'n with Turbo 2.3's for a while.
Boost is addictive and the learning curve is quite steep. Blower pistons are NOT cheap. Got scrap aluminum on my junk pile.