The easiest way is to get the kit from Craftsman that is made to take out screws. It literally takes only seconds to take the screw out using this kit. It costs around $20, but it is much better than ruining a chassis.
1989 Mazda Rx7
greddy t04b, megasquirt ecu, PlX wideband, 12x28x3 fmic, 50mm hks clone wg, ssqv bov, Safc, ss oil lines, walbro fuel pump, tubo intake manifolds, ssac exhaust manifold, 3" dp, 550cc primary/720cc secondary injectors, etc.