Rally/track Car Project Help

Hi all...

First post here so be gentle...bear with me...looking for some advice ref rally car prep....hope this is the right area...
Finally took delivery today of my project rally/track car. Its a Sti Impreza, and it has already been started by the friend I bought the car from. My aim is to prepare the car for use on many of the Impreza drivers club track days..so not looking to pass scrutineering or anything..the car will be road legal....it is however fully stripped and caged..and really just needs the interior finished, cage painted, etc...
One of my first jobs is to properly mount the seats and fit the harnesses..and this is were I am looking for advice....
Does anyone know the legallity regarding harness fitment. When the straps go through the top slots on the seats (Toora Seats) is there a correct angle the straps should be bolted to the eyelets....eg 90 degrees straight back to fixing points or can I mount the straps down with the eyelts in the original seatbelt mounting points........
Secondly having bought prodrive mounts for the seats...only a few of the fixing holes have been made in the seat body...can I just use a standard slow speed drill to make holes for the rear bolts on the mounts to go through ?

any advice on these matters would be appreciated..or if anyone can recommend any rally prep forums that to would be helpful..
many thanks
Paul