throwout bearing collar mount

hi all!
i need to mount a throwout bearing collar inside a trick bellhousing.
the bellhousing (used)was purchased with a large center hole(larger than bearing collar mounting flange diameter)
so i had a piece of titanium welded in the center,a smaller hole cut to center the bellhousing with the lenco.
now i have this question:are the four bearing collar mounting holes on the bellhousing supposed to be threaded or is the collar bolted to the lenco through the bellhousing?(so the bellhousing would be "sandwiched" between collar and lenco?)
what hardware(screws/studs?) is most commonly used to secure the bearing collar in place?
thanks a lot for any input/advice
cyril

 

just got the perfect answer from Nitrobandit with pics!
thanks a lot!
cyril