Well , Bolt are the worse possible thing you could do . Those threads in the head don't need the wear and tear.
The studs you found ... do they leave enough thread sticking out to hold the exhaust flange on ? Long thread into the head. If they do then go for it and use high temp thread lock or exhaust putty to help them stay put. You don't ever want to remove them once they are in place.
If you ever did need to take them out you can heat the studs to glowing red hot to break them loose , then let them cool , then heat the aluminum head to swell the hole and they will screw out as easy as they went in.
You know what we mean by using double nuts to screw them in don't you?
Just a little putty on the threads now ... you don't want putty at the bottom of the hole , just a little to fill-in the imperfections in the threads and supply some lube for installation .
Heating the Aluminum holes and leaving the stainless steel studs cold should let you just snug them up when you put them in. Don't under-estimate the size difference temperature makes on metals ... be careful not to strip them when ya snug-em-up ...
Don't nobody Loves your baby as much as you do ... take care of it.