[TheForge] Nickel rod question

[Barking Crow]

This evening I've been repairing a large chineese vise.  I welded the  part
with the female threads back on to the circular piece that screws into the
largest  tubular piece (the one that attaches to the base).  It's where most
of them break, in my experience.  Anyway, I used a 55% Nickel rod as the
vise seemed to be cast iron and since the 99% Nickel rod cost twice as much.

My question, Is that the best rod to use for this and how do you decide when
to use which of the nickel rods.  It seemed to work well, though I haven't
tested it yet as its cooling in a bucket of vermiculite.  The package said
that pre and post heating weren't necessary but just in case it might help I
preheated with a small propane torch and am letting it cool slowly in the
vermiculite.  I also peened around the piece with a small ball peen hammer.

So, how'd I do?

Thanks,  Jeff Valentine