Depends on your goal try 600mg test blast and see the results, if you arrive at the point wher no matter how hard you train and how many calories you ingest the only results you get is getting fatter then you have arrived at your maximum potential with that dosage. You have two option at that moment: increase dosage to 1g or call it a day and be happy of your physique.
Don't do orals, just do only test if you are worried of your health and longevity. Orals are not worth it unless you compete or you are ok with the toxicity and lipids wrecking. I loved orals in the past but I have quit using it, just a bit of anavar for nitrogen retention here and there once a year and max 40-50mg a day no more.
You can get a great physique on only test. Cut on TRT dosage, bulk on blast dosage and enjoy your life