its opinionated because there are verry few who play with this.

titanium retainers are extremely strong. so would be a good choice for a high revving engine (just because the valve springs are so strong and apply so much force).

as far as valves go, my opinion was for bigger valves instead of a higher lift and stronger springs. you can keep your stock spring setup and have bigger valves. it is a it more for machining, but in the endit will last longer.

as far as a CTR/ITR setup on the top end, it will work wonders and you can find a good many out there. the cams and valvetrain being oem will mean availability from dealerships if needed.

good luck.