i dont see any con in charging an engine with more aggressive cams, i wud say just go for it sir.
dat depends on the tuner, ive joshua thiran of millennium motorsports done it, naturally ud get better results if using a standalone. ive even see he tuned a non-variocam engine to produce high value torque curve, the best tuner i know.
a set of 308, with a higher compression pistons, i prefer the 92 pistons, more flexible in fuel quality or else get the mivec's set or aftermarket pistons, a thinner head gasket, lighten and balance the internals, compliment all those by a set of properly sized zorst, get all of those tuned by a good tuner, wallaaaaa..