Odot thats a question with very simple answer :
1.) higher formats = minimum 120 films
better 4x5 inch or higher
2.) Low speed = minimum ISO 100 better ISO 50 (PanF) or lower ISO 25/ISO 12/ISO6
3) PULL Deveopment but the sharpness comes a little bad - as you might know you can't get both (highest sharpness with extreme fine grain) and also tonals suffers a bit from too much pulling.
Last have a try with Delta 100 E.I. ISO25
recomanded developer : PERCEPTOL/D23/Microdol-x.
Have a try with 135 films if you then notice grain - change to 120 films.
Bon Chance
PS : With 4x5 you are save from grain in
max. 1m 40cm x 2m....


If this is not enough to you have a try with special emulsions or use 5 x 7 (just to come a bit over 2 meter )
If this isn't enough you have to use 8 x 10 but then it becomes a little more expensive

But Do you need 2,60 m x 3,90 m ?