Some of the "SU tool kits" include such a tool, along with a wire
rigging that you put in the tops of the pistons to determine if they
both lift the same amount and at the same time. They also included a small
wrench for turning the jet adjustment nut. I had one once but somehow
it got away (maybe when all my tools were stolen in about 1973).

Being the lazy so-and-so that I am, I try to reduce the number of steps
and particularly the number of assemblies and disassemblies of items as
that is the source of a lot of damage.

Since the needle and the jet are of similar material, I suspect that it
is not unforeseen that they should occasionally be in contact, in fact
the needles do wear against the seats. It seems to me that this is probably
a lot more of a problem that putting the needle into the jet all the way
and tightening the jet, which you would only do once upon assembling the
carb. It has worked fine for me and I have not noted any particular trauma
to either of the parts. So like setting timing with vac connected (and allowing
for the amount of change), this is one of my "self-authorized shortcuts".

BTW when installing timing gears, be sure and doublecheck the timing marks
before installing the timing cover. I failed to do that day before yesterday
and it cost me about 3 hours rather cool and wet work. (speaking of shortcuts)
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma