In 227g dark chocolate where 60% is cocoa, it suggests there is
0.6 × 227 = 136.2g
There is 136.2g of cocoa in 227g dark chocolate where 60% is cocoa.
You need x amount of dark chocolate where 54% is cocoa
0.54 × X = 136.2g
Rearrange the equation to make X the subject
136.2 ÷ 0.54 = X
136.2 ÷ 0.54 = 252.2g
So you need 252.2g of the dark chocolate with 54% cocoa.
A thing to note is baking is very precise, by adding more of the chocolate it could alter the texture of your bake if you have to melt it as the mixture would be more liquid. If you're keeping the chocolate in chunks, it may be ok. You could just use the same amount of chocolate with your 54% cocoa but it'll just taste slightly different as it'll be less chocolatey.