I co-worker has brought me an interesting welding job.

Hammer from a rather old revolver, it is broken in two at the thinnest
part (of course), the section through the break is about 1/4" square.

Big trouble is that there are two holes, one on either side of the
break, one of which has a 1/4dia. by 1/16" counterbore. I'm fearful
that too much heat will ruin these holes.

He is not planning on making this piece back into a shooter, but would
like it to be able to be handled and operated. I have both a tig
machine and a plumbers torch, and I am torn between silver soldering it,
tig brazing it, and welding it. I think in terms of added heat and
potential disasters, that soldering is the safest of the options. Will
silver soldered steel hold up to use, is there prep that I need to do?
I've silver soldered brass and copper stuff but never steel. I assume
the same flux will do.

The hammer is currently fixtured up on a piece of aluminum with the gap
neatly closed up, but now I wonder if I should have used steel so the
hammer will expand and contract at the same rate as the backing plate, I
chose aluminum to reduce the risk of accidentally attaching the hammer
to the fixture.

A secondary consideration in choosing a joining method is to use a
filler material that will be reasonably easy to file away where it
interferes with the re-assembly of the revolver.

Am I looking for something impossible?

How would you approach this problem?

Thanks guys.