Thank you Didier and Urban.

>I think you can compile your kernel with any version of gcc 3, 4 or 5, but
take care of the C library. The libc used by your OS (ie glibc) must be
compiled with the kernel headers for the kernel version it runs on.

So to be clear...if I download the sources and I compile them with the
tools actually on my system, do I need the relative linux-headers package?
building the modules will be OK ?

>Assuming you are using apt-get, did you try installing with
the --no-install-recommends option?

Your assumption is right and I have the recommends disabled in
preferences.d (as per chillfan guide)

Now that I think of it, I got rid of libsystemd0 by having gvfs and dbus
installed from angband repos, might it be that I need to reinstall some
packages from there, but ascii repo (it will take a bit of system
pinning,though)?

In a previous discussion Hendrick Boom suggested it as an easy solution,
but do you recommend having mixed source (ascii/jessie)? I am afraid I
could mess up my system regretfully in the long run....even if only for the
kernel...

Antonio.