I hope that's good enough for your purposes. Full support of 64 bit fields would take a lot more changes.

That 32 you changed near line 394 interacts with some harder to change things inside the reverse method. If you had left it 32, then the MSB feature of Makehex (which I guess you're not using) would work for fields up to 32 bits. By changing that 32 but not changing reverse, you made the MSB feature entirely broken.

Sorry so much needed to be changed for full support of fields over 32 bits. I really wasn't expecting anyone to need any fields over 32 bits.