Kris,
You are asking a question with a potentially very wide range of answers!!! But you knew that already!
The correct answer is: it depends! How much do you want to spend? Where do you want the power / torque to be for your driving style? What is your definition of revvy?
As a starting point to a vague answer, here are some thoughts:
This is a good read if not seen already ...
https://www.viczcar.com/forums/topic/4286-overview-of-l6-engine-heads/
Some have bored out from stock 83mm to 86mm to achieve 2.8L without issues (Rob Gaskin used to race one I believe), others believe it may leave the linings too narrow and consider 2.7 to be safest limit - can’t recall what mm.
Some have used a 260/280 crank to get more stroke / torque and displacement.
Most modified engines aim for static compression in the region of 10 - 11, but that depends on the cam and fuel you plan to use. Flat top pistons, a shaved head and the right head gasket get you there. There are lots of online calculators for this.
Some use lighter forged pistons and rods that weigh half as much as the stock items. Datsun Spirit do some nice ones, but there are many others like JE etc ...
https://datsunspirit.com/shop/dsi-l28-forged-pistons-for-use-with-l28-size-rods/
Depending on which E88 head is on there, you may wish to go bigger valves. How about lighter valves?
For high revving, a couple of wise men I know recommend Schneider springs and caps. (Don’t ask me specifics on which ones).
Stock cams run out of puff between 5-5.6k rpm. Some run cams with over 300 duration. 275 to 280 appears to be a good compromise from the stock. See here for stock cam variations ...
http://xenonzcar.com/s30/cams.html
Mine on a 270 degree cam with .48 lift, 10.5:1 compression and stock L28 pistons (F54 block) revs very happily to over 6.5k rpm (although I don’t often go over that). With forged pistons / rods and fully balanced bottom end you can go further but the engine is an ecosystem and other things have to match / be in tune with it (e.g. cam, compression, exhaust type etc). If you want an 8k rpm motor then rethink your distributor and consider a crank wheel triggered timing setup! Get a kameari chain sprocket and tensioner.
With a revvy NA engine be prepared to sacrifice the bottom end. But you know that yourself.
Some use a turbo to get the best of all worlds - although I don’t know if that is possible with DCOEs.
Some have used Jenvey throttle bodies and get superb fulling / tuning as well as that glorious induction sound.
https://www.jenvey.co.uk/support/faqs/heritage-throttle-bodies/
Outside the engine:
Get a Kameari fluid damper with the larger pulley - your high revving crank will thank you for it!
I run a fidanza aluminium flywheel which makes the car lovely and rev happy but no drivability issues. Sure, there is a difference at crawling speeds but not so much that makes the car a pain in traffic.
Don’t go too big on exhaust manifolds and back pipes.
What you are trying to do has been done many times and in many flavours - do a lot of googling here and on “hybridz” as well as reading this book (considered to be Holy scripture) ...
https://www.amazon.co.uk/Modify-Your-Nissan-Datsun-Engine-ebook/dp/B0092WMDCK/ref=nodl_
Good luck and watch the £££s!! They tend to run away fast when you go down this rabbit hole!
