Thanks for the comments Tony.
A lot of the points you've made relate to parts that I already have purchased/acquired for my gen2.
I already have COPs and NA cams for a start.

I think you have just convinced me there isn't much benefit to a gen4/gen5 compared with the mods I have available to my gen2 already.
I just need to find one of these many gen2 blocks to start the rebuild.....

Biggest thing to reitterate - if you build a Gen2, either go a gen3 sump with gen3 oil pump with gen3 oil pump cog and gen3 timing belt, or get the highflow ATS Racing oil pump (or model 5s Toyota oil pump) and Gen2 sump and Gen2 timing belt or a gen4/5 set up. Need to increase oil flow at pump capabilities. Gen2 has a weakness of oil pump flow in comparison to revisions there after.

And lastly don’t skip little things that you know haven’t been done, like new valve seals, like hose from hell, oil cooler orings, distributor orings, new gaskets (oil pump etc), remove and clean your oil cooler, little things to make it reliable for the future for things that are a nightmare engine apart kinda operation.