6v to 12v wiring question '55 Bird

[birdboy]

I am doing a 6v to 12v conversion on a '55 Bird. I have all the bulbs and did all motor wiring with a 10 si alternator, I now have neg. ground. Some questions:

Do I have to rewire (back of) gauges, this would be the temp and gas gauges?

I have changed the tap on the clock (+ to-), but what about the wiring to the clock? I have a double set of wires going to the case stud now.

The bulbs seem to large #57 12v to replace the smaller 6v in the turn signal indicators. I actually broke one green lens due to the bulb being too large. Is this the correct size number bulb?

Thanks......