Hi there, so you are asking which is the best board for those sails/which are the best 2 boards?
ok. for one board solution, I would say the Falcon 115 or 121 are both good - the 115 is great with 7.7 and 7.0, can work with a 8.6 but that´s the max. The 121 is great with 7.7 and 8.6, 7.0 is a stretch but will work. 38cm works well in 115, but need smaller for stronger winds. 40cm for the 121 is ok for 7.7, may need a 42 for 8.6
Jag 125 will work ok with those sails, 135 is too big. Jag vs Falcon depends on what you expect in terms of performance/gybing, you can check the product pages and comparison to see the difference, but if you already have race sails and fins, then it sounds like you should get the Falcons?
2 board solution is definitely the better choice, to cover more sails/range- then it would clearly be 115 and 140 Falcons. Fins 38 good for the 115 for 7.7, need a smaller one for 7.7. For the 140, 44 is good for powered up 8.6/7.7, the 46 then for underpowered 8.6?
2 board solution for the Jags, I would go with 108/125..