Welcome the forum
S/h 370 prices are knocking on 20k nowadays
Mention has been made about the last 350 model with the necessary bonnet bulge for 309bhp HR engine. But be aware that bonnet is a popular mod for earlier 350's, when you are looking
Having had 276bhp; 296bhp engined 350's and now the 326 bhp version in the 370, there is really not a lot in it performance wise on the road. In my experience, and in standard guise, the 276 engine was more suited to the 350 - the extra rev range of the 296 really only coming into its own on track or long straights. The 296 has slightly less torque, which is what matters in everyday driving. But then the facelift in 2006 and onwards did mean you had a better cabin and other desirable bits, like LED rear lights. Bear in mind also that models pre March 2006 pay the lower road tax, which makes absolutely no sense but good luck to those owners.