UTW
As long as you appreciate that you are really asking how long a piece of string is, the answer is: yes.
As ball park figures they are not a million lightyears out.
However it very much depends on what remedial work needs doing.
If the mount is well maintained and of a type that has had all the AD work done in the past with no new ADs coming out every 2 seconds you could get some change out of the figures you mention.
Dont go spending it though. Something will go wrong and it will cost so keep it in your miscellaneous fund just in case.
For the engine allow cost of overhauled engine (depending on size and make) divided by the amount of hours at TBO. Put that aside for the overhaul and half of that again for a top end job at the midway point.
Expect to pay around the £30 per hour mark for a licensed engineer.
And always allow for the dreaded VAT.
FD