Given that Windows 8.1 is largely a 'cosmetic' improvement on Windows 8, I can't see why any machine that can handle W8 can't handle W8.1. So (if you're determined to switch to W10) I'd still recommend trying to get W8.1 first.
Further, the only software I know of that 'changes' W8 to W7 is again purely cosmetic. i.e, it makes your desktop look as if you're running W7, which makes it far easier to find your way around, but your computer will still actually be running W8. (If it's the excellent 'Classic Shell' that you're referring to, that's most definitely the case). So such software won't help you anyway.
I'd also have to ask WHY you want to switch to Windows 10? All of the technical press are saying that it's best to wait until the problems are sorted out and indicating that it's best to stick with the excellent W7 (or W8 + Classic Shell) at least for the present.
I'm using Windows 7 Pro and I'm most definitely NOT switching to Windows 10 at present. Indeed, given that my system only has 2Gb of memory (which is theoretically enough for W10 but will make it run incredibly slowly) and that I've got devices - such as a graphics tablet - that might not have W10 drivers available (and I'm also currently using XP programs in compatibility mode) I very much doubt that I'll ever switch to W10 until I get a new computer.
Stick with Windows 8 (or 8.1 if you can work out how to get there) plus Classic Shell!
http://www.classicshell.net/