9 starters 3 flywheels? why!!
#12
#14
Big block and small block chevs in some cases had a bracket on the end of the starter to combat flexing and stop breakage of the nose cone. You need to check the depth of engagement of the starter pinion gear in the flywheel teeth I believe you should have about an 1/8th inch between the top of the starter pinion gear to the valley of the flywheel teeth when engaged.easiest way is to disconnect batteries and remove the starter solenoid so you can manually engage the gears. If the gear is too far out shims could be added to the outboard side of the starter. If it is too deep shims can be used as normal to move out the starter. In some cases I have had to file the mounting face of the starter to move in the pinion gear could also have it machined.
#16
not sure if you were asking me about helicoils. if you were you could do it yourself easy/cheap. you drill the holes where the threads oversize, tap them, then thread the inserts in and break a little tab off. you can get a kit at any auto parts place as long as you know what thread/size your bolts are. you might have to buy a tap driver to turn the tap. if you have never tapped anything before i would look for instructions on the internet because you can break the tap in the hole easily. you have to use oil and tap 1/4 to 1/2 a turn at a time. when you turn the half turn or so, you have to turn the tap counter clockwise a bit, (say 3/4 turn) then clockwise again to keep it from jamming/breaking. if it breaks in the hole its a bitch to extract the broken tap