With your engineering background, it's worth telling you that Nissan did a good job with the initial development of the VQ35DE. Assuming the 60K major service was done correctly, you should still consider changing the gearbox and diff fluids and upgrade both to high-quality synthetic lubricants. For engine upgrades, bolt-ons will offer negligible gains, unless you get a tune. Look at companies like UpRev for a successful tuning suite.
Not sure what you mean by a "forged engine", as that's a popular term, but no such animal really exists. Yes, you can upgrade some parts (connecting rods, pistons, ARP fasteners, etc.) with forged components, but that depends on what your goals are. Do you have a priority list of goals for this car?
dkmura's advice is solid. The key is "goals" as he said. Straight line speed, track performance, fun--for-the-hills weekend car? Only after you
honestly establish those goals can anyone make logical, true gain suggestions.
Sounds like you are after power. So, what are the goals of this? What's the condition of the engine (mileage and such)? Do you want just a
little more get up and go or full on gonzo FI monster? So many questions.
Again, as dkmura mentions, bolt-ons are somewhat inconsequential for a street duty car. You WILL need tuning along the way, especially if you start modifying internals (cams, compression, FI, etc).
Word of caution: a true JDM car in the states may be harder to work on from a parts/tuning perspective. Because of the RHD configuration, things like headers, transmission actuation parts may be unavailable/not fit. Even tuning via UpRev or other may not be and option stateside due to completely different ECM settings (guessing). Parts and such to fit the car may have to come from Japan and that will assuredly raise the costs and availability of parts.
Finally, what's your budget, vis a vis the goals established?
PS Personally, if I owned a RHD 33, I'd service it from end to end and "blueprint" to status quo/reliability, do a mild suspension, swap out the rolling stock and drive it that way. Its something of a novelty here so I'd enjoy it like that. But that's just me. Either way, enjoy!