Yes, with electrolytics it's usually OK to go up (sometimes quite a way up), but never down.
In a pinch, wiring two caps in parallel adds their capacitance together. To keep life simple, I normally do this with two caps rated for the same voltage. (If you use caps with unequal voltage, the voltage rating is the
lower of the two.)
For example, you need one 150mfd/150v cap. Wire two 80mfd/160v caps in parallel and you have one 160mfd/160v.
<deleted dumb remark about equalizing resistors>
The article at
http://antiqueradio.org/recap.htm has a little more info about combining caps to get particular values.
I find Mouser's filtering system a little confusing at times. If you are too specific when searching for a certain value, you may miss values a bit higher that would work fine.
Phil Nelson