. Some food for thought.
R
Here's a bit more for an indolent crustacean
If you have 650 engine and it's in good order you don't need any upgrades in order to enjoy the car in modern traffic.....that upgrade has already been done.
In town where 30 and 40 mph are the speed limits you will not struggle to keep up with traffic.
When you hit the 60mph zone you will easily achieve that speed without impeding other road users.
You will be able to exceed 60mph
(I can't say by how much), but at higher speeds the engine will be thrashing quite frantically. This will also be the case if you upgrade anything on the engine to make faster acceleration and a higher, theoretical top speed a reality. Then you might feel the need to modify the gearbox to have a higher ratio; something that seems fraught with technical difficulties.
Anyone who really wants to be able to cruise at 70mph and above in a 500 has maybe bought the wrong model of 500
or should look at another type of car altogether.
In summary, although I understand the attraction of modifying engines and cars of all types, in my experience, especially with the 650 engine, there is no pressing need to fiddle with anything. I would spend your time and money on making sure that the engine as it exists is serviced and adjusted thoroughly to ensure that its inbuilt robustness is maintained.
(As for electronic ignition, I can't see how it will increase the power of the engine although in some circumstances it will help with reliability.)
There....I said it.