If it's a hydraulic lifter build, then little point in improved rods, because you'll be inside the "safe" threshold of standard rods anyway.
What are improved rods? I can example numerous failures I've seen with poor quality aftermarket rods (PEC, DP, Cat cams included, happy to provide pictures and details for anyone that questions it), down to basic design flaws, questionable materials and manufacture. You'll struggle to find much else for sale though, because all the dealers/suppliers favour the products with a low price and good margin and just blame whoever assembled it if it goes wrong. I've NEVER had a failure with the preferred rods I use (Arrow, Robson, Carrillo), even with total loss of oil supply and deep into 5 figures rpm; but every engine I built in the past with lower quality rods has given me a problem, eventually (fatigue).
Note also that the package prices on Ebay for "Wossner pistons and forged rods", are not Wossner rods in any I've seen, but the PEC ones. Not that I'm holding up Wossner as a brand of quality, but the offer is worse than you think!
The broader issue, with rpm and power, is that you do not need to rev the crap out of an N/A engine to make good power. My best TU race engines are making over 200bhp at 7000rpm. Power is simply torque multiplied by engine speed. If you make enough torque, you'll get the power at lower rpm through better efficiency. It's that simple. Getting high torque from an N/A engine is not easy though, so in most cases engine builders just work towards revving the engine more, to make the torque they can at higher rpm and see a higher power figure that way (exaggerated by rolling road testing, which tends to make power appear at higher rpm due to transmission loss characteristics compared to a true engine dyno). If you focus on "flow" development, that tends to be the kind of engine you get. Improving torque at moderate engine speeds takes a much more detailed approach to the overall inlet and exhaust pipe designs, chamber design and the cam/compression relationship with the rest. The overall engine performance tends to be much better with an engine developed in that way.
More than anything, I would encourage whoever to think about efficiency more than increasing rpm and to try to choose components that will work well together within your budget and a sensible rpm limit, rather than spanking large amounts on aftermarket rods, the money might be smarter spent elsewhere!