Why not giving cure 1 1.5sec gcd instead of 1.5 sec cast ? That way, it will heal a little bit more than cure 2 par sec (333 power/sec for Cure 1 and 320 power/sec for Cure 2) and even cost less (267 mp/sec for cure 1 and 533 mp/sec for Cure 2).

If we increase cure 1 cost to 450mp, it will cost slighty more than benefic 2 per second. (300 mp/sec for cure 1 and 280 mp/sec for benefic 2)
At this point, let’s reduce cure 2 cost to 700mp so it’s less weaker than benefic 2. (same mp cost and power but still longer cast time)