Type 61 is probably not really suitable for a choke type current balun for 160m, and definitely not in a smaller core size like a T140. The AL of the FT140-61 is about 120, about 1/10th that of the higher permeability materials like Type 43, 31, or 73/77. You'll find it difficult to achieve sufficient choking impedance to get good common mode suppression on 80 and 160m, as you're really looking for something on the order of 2,000-5,000 ohms. You just can't cram enough turns on those lower loss materials, and you don't want low loss to begin with. A 1:1 choke type current balun only works because the material is lossy.
A truly effective and low loss 160-10m balun is a bit of a tricky creature to construct, because in order to get good common mode impedance at one end of the range, you'll likely have to sacrifice to some degree on the other, either by injecting additional loss on 10 meters, or accepting somewhat reduced impedance on 160 meters.
You'd do best for the entire range with something like an FT240-43 (which run about $4.50 from Mouser), with 14 or so bifilar turns of good quality magnet wire on the core.
Given the current status of the solar cycle, personally I'd probably opt for something like a T240-31 with 12-14 bifilar turns, knowing I was injecting some loss on 10m and to a lesser extent 15m, but getting better performance on 160 and 80m. Most of the action for the next few years will be on 80-15 meters, and a in a couple years that will probably drop to 160-17m before starting to rebound.
This document is often referred to as the "RFI bible" or "Balun bible", and with good reason. All the knowledge you seek is contained within, and in fairly easy to understand language. It's well worth a read and, in my opinion, should live on every ham's bookshelf.