The wonderful thing about Spitfires is all the combinations of motors, gearboxes, diffs and suspension set ups that you can use and your car will still be a Spitfire and not a “hot rod”.
Although I am not greatly in favour of modifying things or turning these beautiful little sportscars into hot rods I must confess to some modifications on my MKIII Spitty, which involved a later model gearbox and suspension.
The suspension modification was simply the fitting of a MKIV rear spring and front sway bar, changing over to Koni shockers and fitting better wheels and tyres. A simple modification that was worth the effort. The other modification was the fitting of a MKIV gearbox which gives slightly closer ratios and syncro mesh on first gear, the latter being the expensive modification and probably worthwhile.
My MKI Spitty has no modifications apart from an oil cooler and a smaller steering wheel, I feel this makes the car more interesting in some ways as it is original.
In Europe where there is a very large following of Spitfires the conversion to a 6 cylinder motor is very common.
Some members have gone to great lengths to modify their Spittys, but I guess one of the most interesting, being the fitting of a GT6 rear suspension to a 1500, this change would no doubt make this Spitfire into a Lotus beater in the handling stakes.