HI Chris and a very Happy Christmas to you too.

To do what you're asking I would personally go down the RealBand route.

Open your saved BIAB track in Realband > Go to the Track view (waveform view of all instruments) > Select a new track and highlight the bars you want the solo fit into > right click and pick Multi Riff (choose) and select your Brent Mason solos. RB will generate around seven alternatives which will fit and you can pick which one suits the song best. (If there's nothing you like from that choice just repeat the process and RB will generate another selection to pick from. Providing the solo samples are reasonably close in tempo the tempo will be adjusted automatically (to 120bpm in your case)

The resulting song and solo(s) can be mixed and reverb etc applied within RB.

Hope that helps some. Other more experienced forum members may have other ways but that's just how I'd tackle it.

Best wishes

Kev.

BIAB 2022 PLUSPAK (ext HD), 49PAKs, STYLESPAKs 1 - 6, Win 7 64bit PC, REAPER, Ozone, Adobe Audition CS6, EZ Drummer3 + EZ Keys,Soundcraft MTK22, Behringer X Touch Universal Controller,, SE Gemini/Rode NT2/Neumann/Shure mics