I have enough trouble with one driver, let alone two.
I have an Epic Flash set to 12.5º. I just ordered an Aldila Quaranta 40 gram shaft in senior flex for it. The driver is 45.5 inches, but the fitter told me that is like 43.5 for the average golfer (my irons and wedges are +2-inches).
I will go against my regular reluctance to not give recommendations - but this comes from the "if you think the Aldila is not giving everything you want department."
If you can find a Mitsubishi Grand Bassara Shaft at R flex, 43g, as a pull somewhere, something like that might be a consideration in the future. Callawaygolfpreowned would be a good place because some of their prior drivers had that as a stock shaft. So many good shafts out there. I am growing fond of Accra - the FXS 2.0 100 series may be one to check out. I am consistently surprised at what a shaft will do for distance and dispersion. I use a TPT Red fitted shaft in my driver - lively with tight dispersion. Shafts are fun.