You can use a receiver with an FBC tuner without a unicable LNB. However, you will not receive full benefit.
With a universal / normal LNB, tuner config will be exactly the same as you have on the solo2. E.g, simple, single, 28.2.
This applies to all tuners with a signal wire.
You can actually record more than 8 channels with your solo2 as it is. But because you have two tuners (both connected to a dish) you are restricted to two transponders.
An FBC module/tuner consists of 8 tuners, but only has two physical connector ports. When you use it with a universal /normal LNB, 6 of them will be in loop through mode. This is because of the way a universal LNB works. It switches between the four bands/quadrants. High, low, vertical and horizontal.
Because the a unicable LNB does not do switching between high/low/vertical/horizontal, you can configure 8 tuners of the FBC tuner to use individual use bands that the unicable LNB communicates on.