$\def\argmax{\operatorname{argmax}}$ One mate told this problem about a game and its optimal strategy:
You have infinite cards with 1, 2, 3, 4, or 5 as their value. You can make a deck with any of this cards you like. Now, the other player says a number from 1 to 5. The deck is randomly shuffled and the first card is taken, if it is the said number you pay as much as this number to the other player. Otherwise you lose nothing. The question is, what is the optimal way of forming the deck?
I've reached the conclusion that having 120 ones, 60 twos, 40 threes, 30 fours, 24 fives seems to be optimal. The reason is that the second player is going to always say the number $$\argmax_j\{jPr(X=j)\} = \argmax_j\left\{j\frac{x_j}{\sum_{i=1}x_i}\right\} = \argmax_j\{ jx_j\}$$ where $X$ is the first card, and $x_j$ is the number of j's in the deck. Given that, having all the quantities $jx_j$ equal seems to be optimal but I can't see why.
With the composition of the deck as you proposed, you are losing on average 60/137 in each round no matter what player B says (if he says 1, he will win 1 with a probability of 60/137, if he says 2, he will win 2 with a probability of 30/137 and therefore the expectation value is again 60/137. The same for 3, 4 and 5).
Let's assume you change the composition. For instance you replace a 2 by a 3. Now you have 41 threes out of 274 cards. Player B realizes this and he will always say "3" to increase his chances. The expectation value for his win will now be 3*41/274 which is a bit more than 60/137.
So whatever number you increase in the deck, it will increase your losses.