Been a while since I worked on a chevy but I think you will be fine,
just unbolt it from the flexplate and then fit it into the front of
the trans, make sure it is fully engaged, then reinstall as normal.

nate

To the best of my knowledge, you should be just fine. Pulling TC with
engine is fairly routine, albeit usually somewhat messy as the TC dumps
its fill of ATF all over the garage floor. (Unless, of course, you've
planned to do so, and drain the rig before starting)

Word of advice, though - Don't know if it holds for Chevy products, but
on some Fords, the "socket" on the TC that mates with the input shaft of
the tranny has two "flat spots" on the outer circumference. Fail to line
those flat spot up with the corresponding flat spots inside the tranny,
and as you tighten the bell-housing bolts during reassembly, you destroy
the front pump in the tranny. A couple of years ago, my former landlord
had to have a previously working tranny rebuilt three times in 2 weeks
before figuring out what it was he was doing wrong. It's quite unlikely
he'll ever make THAT mistake again...

Apparently the outer part of the TC meshes with the front pump via those
two flats. Fail to line them up, and you fatally crush the front pump
when you bolt the bell-housing to the engine. And it doesn't take much
at all to do the damage (you only find out for sure when you fire up and
try to drive away after reassembly is complete - there is little or no
indication that your alignment attempt has failed until then)