It's all diet and nothing to do with drugs. Drugs will help facilitate a certain size but you need to eat to attain it. It's like trying to build a house without any bricks. I love high deca. I have mixed views because for you it's pretty pointless going really high because you are not eating to make the most of it. In fact for you going higher with drugs may even go against you. At the same time if you want to run something go for it but do it smartly and ramp up the dose gradually and see how you respond. As you ramp up the dose you need to be doing the same with your nutrition. Quite honestly if you don't eat sufficiently it won't really matter if you do 600mg or 2g of deca.
600mg deca is more than enough for you to grow on. I don't have great genetics but when I go up to about 270 I will start at 500mg test and 350mg nandrolone (probably npp this time) and the most I will go up to is around 750mg test and 525mg npp and that is more than enough for me. When I tried high deca I think I tried 1.2g but I can't remember and would need to look back at an old log. I should add I usually hate (massively) when guys go on about their own doses and expect everyone to do and respond the same especially genetic freaks on 500mg total saying to some guy with awful genetics if you can't be huge and lean on 500mg you are somehow doing things completely wrong. I literally cringe when guys talk like this but I do it for a reason with you because it's obvious to me by your posts you are simply not eating enough. If you were eating enough you would know 600mg deca only is more than enough for you to grow. If you were eating massive clean cals consistently and struggling to grow I would say sure up your dose but that is not the case.
So instead of thinking about 2g deca why don't you draw out a starting diet and stock up on quality food and maybe some "diet hacks" in case you struggle such as weight gain shakes (make your own), intra shakes and nut butters. You are not tall but I believe you're 5ft 7 so regardless of your genetics getting over 180 should be easy with consistent food and anabolics.
I just read you struggle to eat 4000 cals and there is your answer. That is nothing. You could eat a typical diet of beef/chicken and rice with fruit/greens and get in about 3000 cals. Then you add a large shake with protein, oats and almond butter pre bed and there is your 4000 cals for the day and all you had to do was add in 1 shake to your existing diet. Not everyone can eat loads of clean food consistently but 4000 cals is nothing especially when you can use certain methods/aids to bump up the cals. A 1000 cal shake pre bed and because of your metabolism (I have seen your pics and condition) you shouldn't get fat if you take your drugs and TRAIN HARDER.
Everyone is different and people concerned with hair like to use deca only but I would 100% recommend a test base (300mg for example) and a little masteron (200mg) to go with the deca which I would start at 400mg for you and you can go up if needed/wanted over time.