It's fitted like that because the TOM style has a limited saddle adjustment range, so the bass end needs to be further away from the nut than the treble side (1/8" or 3mm), in order for the saddles to be in the right area to allow for correct intonation. The Nashville style TOMs have a larger adjustment range than the original ABR style TOMs, so allow a slightly sloppier fitting (plus a wider range of string gauges).
You won't want the string ferrules too close to the bridge position. The strings should travel from the top of the saddles down to the body without touching the rear of the bridge. Make the holes too close and they'll catch it. So you'll need to work out where and how high the bridge is likely to sit, and then use a straight edge to determine the nearest position the string-through ferrules can be (allowing for some deviation from your estimated bridge height). An adjustable height stop-tail is a lot easier in this respect. You won't want the ferrules too far away either. You'll probably have them between 60 and 90mm back from the bridge (the higher the bridge, the further back the ferrules need to be). Up to you whether you want to use straight, staggered or curved lines for the ferrules, you can find examples of each type searching on line.
https://uk.images.search.yahoo.com/s...F-8&n=60&x=wrt