Your question is far to vague to give a specific answer to. For that reason, the answer is both yes and no.
IT all depends on how you plan to get 12% more area.
If you do it as a combined function of adding more lift and duration to the lobe, it might not be agressive.
IF you do it soley by adding lobe lift, the cam will surely be more agressive and, if you are velocity limited by way of tappet diameter and/or other such limitations in/of the follower mechanism, you might not even be able to do it this way.
If you do it soley by adding duration, low speed performance will suffer while similtaneously enhancing high speed power. Again, your useage and/or operating requirements will determine if this is even a viable option
If you do it by adding only rocker ratio (going from 1.5 RAR to about 1.7), the cam will stay the same but your spring and valvetrain forces and stresses will go up drastically due to the more agressive valve action the higher ratio will foster. This may or may not overtax and break something in the rest of the parts in the valvetrain.
I've yet to see anyone who's successfully made cams (especially one offs) on a DIY basis and we make cams for a livelihood. I'd highly recommend first finding an expert to grind your cams for you and then graciously take advantage of their expertise.
Surely there are folks somewhere on the Continent who can help you. You might check "Racer" magazine as a number of European cam makers advertise there.