Will these heatsinks be sufficient for my mosfets?
I would suggest using a beefier mosfet, like one of these for example:
IRLB8748 or IRFB7546, these mosfets have very low Rds(on) of under 10mOhm.

I would also suggest using only N channel mosfets, this makes driving the high side harder but N channel mosfets have lower Rds(on).

With a 10mOhm mosfet you dissipate 6.25W at 25A, which is easy with a proper heatsink and there's no need for active cooling (a fan).

The heatsink you've linked on ebay doesn't specify it's thermal resistance so it may or may not be enough.