Re: Question bout fender stuff
1) The E-to-E, centre-to-centre, dimension on Fender Tex-Mex single coils is the conventional 57mm. This means that, as usual, only the polepieces of the centre pickup align correctly with the strings.
2) Fender/Ping locking machineheads will go right in with just the use of a spanner. Fender/Schaller locking machineheads might go right on without modification. Fender/Sperzel locking machineheads will definitely require a new guide pin hole to be drilled.
The machineheads of your CiI Fender/Squier are almost certainly manufactured by Chin Ho. If you are on a tight budget, Wilkinson EZ Lok machineheads will directly retrofit. Just ensure that you get the version with the hidden guide peg fitting. I usually find that the rough edges around the dual string holes on the posts benefit from being filed smooth prior to installation.