I think that any pens would be appropriate for photorealism and if you do a google search on the subject there are even amazing examples of this movement done in Bic ballpoint!!!
My advise would be to try first in pencil (either graphite or charcoal) and just take your time, I find that proportional dividers are incredibly useful tools too but nothing is a substitute for just being willing to devote a massive amount of time.
Anyway I hope this helps, I am trying to achieve photorealism also and eventually hyperrealism and beyond once my technique develops more.
My advise would be to try first in pencil (either graphite or charcoal) and just take your time, I find that proportional dividers are incredibly useful tools too but nothing is a substitute for just being willing to devote a massive amount of time.
Anyway I hope this helps, I am trying to achieve photorealism also and eventually hyperrealism and beyond once my technique develops more.
