Npp stack < high test?

hello, im looking for advice for my blast.
i have 2 traditional cycles under my belt (250mg test e and 500mg test e), realized blast and cruise is better than constantly pct back up and then crash again.

since then im blast and cruising:
blast 5 months 750 test e
cruise 5 months 200 test e
blast 5 months 750 test e
cruise 5 months 200 test e then pct and try to keep the gains.

right now im one month into the second blast phase and made great gains on 750mg while getting lean in the cruise on 200mg. not really any more sides on 750mg than on 500mg.

now im as i said one month back at 750mg again.

Question #1: I was thinking about lowering the test a bit and adding nandrolone (npp). would smth like 500mg test and 300mg npp outperform the 750mg test gains wise while keeping the sides/risks equal or even lower? (i dont want to add primo [yet], so please give advice to this stack)

whatever i do, test only or the stack in question, im going back to cruise on 200mg test.

This is not ideal. Why would you run NPP long term? You like pinning?
Your also gonna need to add a DHT to this to balance DHT/DHN or you gonna be at higher risk for deca dick. Also the mg per wk you want to run are high if your gonna stay on for 5 months at a time.
This is what I would suggest for your blast phase.

Test-300mg/wk
Deca-125mg/wk
Proviron-25mg/day

If your diet and training are on point you will make great progress on this. More is not better.

so the 750mg test was overkill.

how long should i blast then? 3 months?

Yes, for a typical gym rat 500mg/wk is more than enough. If your stacking other compounds then less.

Agree with @s.gentz. T for me was always in the 300-500mg range max. After that it’s diminished returns with more E2 issues. I would rather run T at 300mg with another compound than just increasing more T. Blasts are usually 10-14 weeks long depending on ester and compound.