Little bit of both...
Now...if someone had the time and money to experiment...
Those shafts are pretty much a straight shot, so get a hardened shaft, milled to a 1/4" x1/4" key and slot the gears to match...Get hardened Keys...
Cut a bigger groove in the ring and pinion gear and replace with steel pieces
Output gear can be left at 5/8" as well and standard chain sprockets are available...
Would it equal a fully built 700?? probably not, but would be a heck of a lot stronger contender than it is now...