Definitely a chestnut base. Also definitely varnish, and a nice big blanket.
Lp often does funny things to colour. Just having a stab in the dark, if the mare isn't too old, I would think she is greying as well as having Lp. However, I am not much of an Lp expert, hopefully ND or Face will stick their head in here
It would be a cool if she had a palomino base! She has 30 days in QT up in NC and then I go pick her up. So once we actually see her in person I am sure her color will be more clean ;) And a bath would help her to!