A few questions about how I should expand further

Im cirrently on Tier 2, I have not built the Space elevator yet, but I have really big problems with the assemblers

So, I currently have 2 iron Plants: 1 with a 120/min drill, going into 3 smelters, 2 of them producing iron Plates and 1 being split into iron rods and the iron cast screws

And now I built a second plant from right besides it with 180/min, going into 6 30/min smelters, however even the mk2 conveyor bottlenecks the smelters

However even this way I still only produce enough screws for the rotors, so I still need another 60/min for the reinforced plates

So since I dont have a third iron node by the next 300m my only options are basically to either turn the whole plant into a plate and rod plant each and get a third one from somewhere to get the screws, or I can just redirect the screws from the other plant and let the rotors lag behind

If anyone had other ideas, I would appreciate it

Also, as a bonus: How in Ficsits godforgiven name can I scale these assemblers? Like, If I need 2 Iron entire Pure grade iron plants to build even 1 assembler for each, and the mk2 smelters and stuff only unlock once I got to Tier 3 or 4 already, how can I realistically even finish the Space Elevator project?