Google Crankworks (Arizona) and Falicon (Florida). The job is expensive--north of $350 at best, with materials. Results vary. For a street engine at stock displacement I'd recommend having the crank blueprinted (inspected, trued and brought to spec) with pins welded so it doesn't come out of true.
I had my crank rebuilt and welded. It had spread apart inside the case. Couldn't figure out where the noise was coming from. Took the crank out and everything looked OK at first glance. Went to set the crank back in the case and it wouldn't fit. That's when I noticed a scuff mark on the inside lower case. Was the rod loose ... rockin'.
No, they're not all the same. Rod length and wristpin diameter changed in 1974 (TS650A). Later cranks won't fit your machine. Look at the parts books at www.biker.net . Any crank assembly with the same part number as the one listed for your '72 will work. A crank does not have to be rebalanced to be moved from engine to engine. Having your crank blueprinted as I suggested is cheaper than a balance job.