1.7.10 mods on 1.8.7 Servers?

Nope. Those two are completely different versions of Minecraft. Now, if it was 1.8 mods, then it could work on 1.8.7.

No, it causes massive issues as well as going about 2 seconds before it dies and tells you it won't work. There were too many changes between the versions for this to work.