Denso NQ22 iridium spark plugs(right heat range to use?)

[TnF]

Hello. I have a 200sx(s13 with ca18det EUR engine-High port)
I have s15 gt28R(stock turbo, 99' version with inconell turbine blades), walbro 255l/h fuel pump with FPR, cone fiter, Stock side mount IC, e-manage Ultimate ECU, Mac (EBC) boost valve(same one used by AEM), z32 maf, 2.75'' turbo outlet(yeah the pipe is coming out 2.75'' in a modified 2.5'' flange), wrapped tubular ported exhaust manifold, innovate LC-1 wideband, act 6-pack clutch, lightened flywheel(not full lightened, stock one trimmed), braided stainless steel turbo oil lines, stock 370cc injectors, thermostat 76.5oC running 0.55bar now. Basically i am in UK now studying Meng, the turbo has been blown last September(i bought it used and it was having CHRA internal problem, after 4 months had CHRA oil leakage and then blown), and i am going to replace it at summer. In my list is a new s15 turbo, small fmic(minimise lag and pressure drop)( i would prefer v-mount but it's too expensive: new hood, radiator, pipes, fans), some other minor things and new spark plugs.

Stock plugs as it can seen in the service manual are heat ranges 6,7, and 8 from hot to cold. So i am planing to run 1bar(hope it can handle it), so i am worrying about knocking. I will run on 98octane EUR(type fuel), there is 100octane but it's too expensive, 102 octane racing only(it can be found in petrol stations in UK, where i don't live permanently) In denso website and NGK they quote heat range 6 on their plugs so is it better to run colder? note: denso heat ranges are: 20>>6 Ngk heat range, 22>>7 Ngk heat range. Also how much colder? Better in 8 range?

Also i will use Denso and not NGK iridium plugs because i've searched, they have better performance, and they have figures, while Ngk doesn't. Another thing is that denso plugs have 1.1m gap but 0.4 tip, so if i get any missfire i will decrease the gap.

Any help appreciated, and out of topic...because of budget, and not anyone in my country which i trust to do ECU tuning(so far anyone touched my car broke something, so i do everything on my own) i will make the ECU tuning byself, so can anyone confirm me if this procedure is correct: correct AFR by increasing, and decreasing the fuel where needed, check for knock and increase fuel where needed, retard timing until knock occurs, correct timing by advancing timing 1-2degs. Also how trusty is the stock knock sensor? Note: temps in summer in Cyprus(where i live) come to 35oC, but with the 76.5oC thermostat and stock radiator with only coolant i was getting max 82oC not even there...more like 80oC...

Thanks, Ken

Edit: i found also that we can use denso IQ01-24 (racing iridium spark plugs) which are almost double the price..
Another question, Will 444cc injectors run fine with the s15 turbo @ 1bar? OR can i use the 370cc injectors and increase the fuel pressure?(though i don't know how much they hold)