It wont hurt to try it, as each case is different.
It is a shame we are seeing an increasing number of cases these days with solid front panels, considering cooling as a secondary priority.
Generally, youd want to avoid top intakes. Your processor will probably run cooler, but youll be forcing hot air from the processor down towards the GPU while also trapping GPU heat down as well. Plus, having sufficient intake is only part of the problem, you can flood a system with cool air but preventing it from venting hot air will eventually heat up the whole case.