There are heaps of packages that will not build under 64, and 64 provides no real gain whatsoever under a bus heavy load with the project code we use.
Gotta understand approx 94% of the "64 bit specific" packages out there do not utilize the extra instruction sets... at all. 64 DOES provide some performance gains in a lot of niche areas... we are not one of them. It would be nice to support it... but primarily that support is so people can "feel" as though it is performing better. It really makes no difference in execution.
64 bit, for the most part, is part of the required "improvement" mandated by Moore's law with regard to marketing by companies who refuse to ACTUALLY move forward to asyncronous processing.
Rants aside... it will not hurt anyones feelings if you fix 64 bit support... however it will require an understanding of our architecture, and probably a full builder... for which there is a lot of magic necessary which is undocumented in 1004.
Drop into IRC if you really want to undertake this arm of development.