The steel crank damper is thin, looks like a lot of other early dampers.
The cast crank has this big fat ugly damper, not to body shame a damper.
By '75, more than likely a cast crank.
What's odd about Chrysler was that with Chevy you had to get the absolute best Corvette engine to get a forged crank, but every Valiant with 225 on the street had one, a forged crank, nevermind all other engines. all of the V8's through 1971.
Things were going downhill fast in '72, I'd guess that's when cast cranks appeared.
A local racer here built many successful cast crank 360 engines/Duster that rivaled big blocks, so they can survive high perf applications.
He was my mentor when I was building my 383. I learned all the ins and outs of block blueprinting from him, deburring, polishing, this is inside the block, peening and polishing rods, chamber squish, porting/polishing heads, overlap, exhaust scavenging, windage, soldering and filing you own advance curves in distributors, etc, etc.