91 suburban gauge cluster temperature sender

[cagodinez]

I'm getting ready to drill and tap my passenger side head on my 5.3 and have a couple questions. I'm going to be using a 91 suburban cluster on my 78 Silverado.

Do I get a temperature sending unit for a 91 suburban or 78 Silverado?

What size drill and tap do I need to buy?

I've heard of people re threading the sender. Does any 1 know where I can get the sender re threaded for the LS head? Any help greatly appreciated.