Sean,

It is obviously a typographical error.

A .61 engine differs dramatically in size and weight, from a .40-.53.
You are likely to need more tail weight, if your model was designed for a .40-.53.

The majority of the added power will go to waste, just carrying all the extra weight.

Your model will also lose much of its agility and will land at higher speeds.

It will be quite a bit more cumbersome...

Are you sure this is what you want?
If not, just stay with a .40-.53 and I am not so sure if the OS is your best choice.