Personaly I think they are having you over mate
. I have worked on engines for years including total re builds and for them to say it could blow at any minite is absolute cobblers.
Ask your self the following:
Are you burning
, if so how much are you having to put in and at what intervals?
Are you suffering a lack of power and do you have any engine rattles. If the bores are as oval as they say then you must get some piston slap on start up.
If the engine is that worn you must have some pretty obvious signs and any or all of the above would be evident.
You say that you have had a lot of engine work done what was the reason for this?
The bottom line is a basic compression test needs to be done both dry and wet. If there is a signiffican t difference between the two and you are burning a lot of
then chances are you engine is worn but at 75000 is not a lot so I wouldnt have thought it could be as bad as they say.
Mine is at 89000 and I thrash the preverbal with it and it is a sound as the day I brought it new.
In the worst possbile case you could always get another engine from a scrappy most of them will give you 3 months warranty on it.