Lighter is way easier to ride (in the woods)!
Many bikes come with "Off-Road Use Only" designations. When I was shopping for KTM, I discovered that they all come with a title from the factory. In other words, they can be registered (with the proper lights added). Light kits are reasonable enough to add.
I ran into a guy couple weeks back with KTM 250 XC-W plated, autoclutch. That was a sweet setup.
I had a KTM 690 enduro R (305lbs) and traded it for the KTM 350 EXC (248lbs) and the difference is night and day. You'll be a better rider on your first ride. I think if you are going to go through all the work to find something... try to stay under 250lbs.
Also, being vertically challenged at 5'7"... I cut 1.5" out of the seat, softened the suspension and wear thick-soled boots. It works without serious compromises (i.e. suspension lowering).
I think you can find a nice used KTM or the like for about $3K.