If you have a guitar you're planning on modifying, chances are that it will be an import or far East built instrument. There's good reason for that, they offer great quality bang for buck resulting in a great base for tweaks here and there than perhaps a more premium, pricier American made equivalent would. Let's face it, not everyone who has just spent £1500+ on a USA made instrument wants to go at it replacing bridges, pickups or making major changes to the guitar, so the import guitar market offers great scope for DIY tweaking. Especially in the current guitar market where there is a HUGE choice of reliable far Eastern built instruments.
Some of the most common mods we are all likely to make is changing out the electronics and pickups, which is something we're doing on a few instruments at the moment. One is our 'Project Offset' Jazzmaster which I'll be focusing on in this post. The Squier Vintage Modified series offer a superb canvas for modding, but they're not without their little quirks which can cause hiccups along your modding journey. I hope posting about these differences may help someone else plan their own project and sail much more smoothly along the way.
One I encountered early on after stripping it all down to it's parts, was that the right angle bracket that mounts the rhythm circuit roller pots to the pickguard is quite different to the standard replacements available. The two mounting screws are located much further inwards on this early version of the VM Jazzmaster, whereas with the USA spec bracket the mounting screws are located further apart. It does appear that on later production run VM Jazzmasters, they were using the US spec brackets which will be easier for you if you have one of those! So if you're planning on replacing the wiring in your early version Squier VM Jazzmaster, I'd recommend keeping hold of that original bracket as you'll need to re-use it providing you're keeping the factory pickguard of course. I spent a lot of time trying to find a source for these but sadly wasn't successful (without having my own produced which didn't seem worth it ultimately). Because of the mounting screws being further inwards, the screws that fix it to the pick guard do also foul the mini pots, which is far from ideal as it can indent the pot casing meaning the internals of the pot could rotate incorrectly/foul the casing. So I had to space out the pot slightly using a washer and spare nut which you can just about see in the below image, which gave enough space for the fixing screw to miss the pot.
For reference, the mounting screws on my early VM Jazzmaster rhythm circuit bracket were - 51mm apart. Whereas the US spec brackets I stock measure 67mm apart.
You'll also notice there are imperial and metric spec mini pots for this circuit. The diameter of the solid shafts are different between those of Alpha and CTS branded items for example. Alpha mini pots have a shaft diameter of 5.96mm whereas the CTS rhythm circuit mini pots have a shaft diameter of 3.96mm. So whichever you choose, be sure to get hold of the correctly suited roller knobs to help relieve frustration upon coming to fit! I wanted to test the quality of the Alpha pots on this particular part of the wiring, which I must admit was also influenced by the fact I wouldn't need to source new roller wheel control knobs as well, as the original rollers suited just fine.
Frets were next up, a check over revealed than non needed leveling thankfully. All were nice and in good condition, no high or loose fret ends which is a great start! Wish it was always like that! So I tidied up the fret ends and dressed them meaning it's much smoother feeling in your palm. No rough fret ends at the fretboard edge. 
Upon re-fitting the neck, and remembering it's original set-up when I collected the guitar, I felt this Jazzmaster would benefit from a neck shim. This is quite common on all Fender guitars, but especially so with Jazzmasters/Jaguars to help lower the action, improve the neck break angle and tension over the bridge. I do highly recommend the Stew Mac angled full pocket neck shims, available in three specs; .25 degrees, .5 degrees and 1 degree. I felt this guitar benefitted from the .5 degree shim. This really helped get the neck break angle set better. 
Thanks so much for reading,
James