How to fix a stovax log burner in place

[browfish]

Just bought a Stovax studio 1 log burner cassette. The instructions provide all the useless information like how to take it out the box, remove the packaging etc, but when it comes to fixing the cassette in place it simply says use M8 bolts. There are no holes predrilled or bolts provided etc. The opening is a couple of inches larger than the cassette as the opening dims suggested are minimums and larger opening would prove easier to install. If I drill the outer box and fix bolts, there would be a void so I could not tighten. Also, how do I level the base?
thanks

 

[Norcon]

Wouldn't take the gift of one of those designer heat losers.

I know they tell you they can radiate most out to the room (pen and paper refuses nothing) but in reality a much higher percentage goes up the chimney and out through the walls compared to an open sited stove where air movement flows around the stove freely and unrestricted.

 

[browfish]

helpful
thanks

 

[Norcon]

You're welcome.