Hey @RampageZA,
Sounds like a good plan.
Grow all of them ;)
Your pot choice is great, moving from a 10 to 40 is a big change but your plant will enjoy that, try and put them in their final pot a week or so before you think they will switch. I have noticed a much better stretch and general growth if they had time to colonize their new home beforehand. The more root the better! Obviously you want to keep in mind how big your plants can get, as outdoor can produce some tall giants if not managed.
As for FF soil, it is quite light on nutrient in general. If you plan on using the soil straight, it might come up short. You will have to supplement with organic teas, bottled nutrients or both. You can look at topdressing your pots but this is a much slower and not as efficient method.
A few items you can look at :
-Quick, easy, expensive - Talborne, Biobizz, Greenhousefeed, pre made fertilizer
-Takes a little longer, more research, cheap - amendments such as Kelp meal, Blackstrap molasses, Alfalfa meal, Insect grass, Bone meal, Guano, Soft rock phosphate, Manure, etc... and all that can also be used in making teas
I have successfully used their soil but it was layered and spiked. In addition teas were fed very 2 weeks or so. It had a lot of extra help.
Hope that helps.