I'm sure you have your reason , but I have to ask whay you need so much bullet contact ?
If you have ever tried to pull the bullets from factory loaded round that has been crimped and one that has been properly neck sized only half the way the factory bullet will typicaly come out alot easier.
Neck sizing your cases only 1/2-3/4 of the way will usualy give you a little better accuracy because the neck is helping to hold the case in alignemnt. You can adjust you neck tension by either using a bushing die and getting smaller bushings or by polishing down the expander ball or your die. I personaly have found that the Lee collet dies are great for accuracy sake and you can get a couple extra neck mandrels and turn them to differant sizes to adjust neck tension