Shift points actually endup just fine, the pcm get's it's MPH info from the VSS which happens BEFORE the gearing affects anything. The speedo will be way off though.
Far as ratio as said concerns about top speed is just ignoring the impact of overdrive.
The Caprice SS was what the Impala SS was sold as in the Middle East(this is where you are right?) even had the deer logos, the Caprice name had history there, the Impala did not so they used the popular name.
That said if a true Caprice SS we are looking at a current ratio of 3.08.
With no converter slip 3.08 at 150mph is 4000rpm which is below peak HP and the aerodynamic drag will usually stop the car from accelerating because the engine is not making enough HP to fight it further.
With 4.10s at 150mph it is 5300rpm which is past peak HP, BUT if the valvesprings are decent the engine will still be making more HP at 5300 than it was at 4000rpm with the 3.08s. The 4.10s will make you rpm limited with the stock engine to about what your top speed would have been with the 3.08s but the 3.08s were just keeping the engine below peak power and limiting you that way. The car will obviously feel a LOT better at lower speeds with the 4.10s. Even 3.73s will make the car feel 1000lbs lighter.
With 3.73s 150mph is 4900rpm which would be pretty close to peak HP with stock valvesprings they might actually be the gear that gives you the best top speed. Stock valvesprings get weak and at higher rpms can begin to let the intake valve bounce when it closes which hurts power a LOT and could happen at the 5300rpm 4.10s would turn at 150mph.
It just struck me I should comment on if this is a basic Caprice not a true Caprice SS, I see the rims in the avatar but just hear me out.
The 2.93 gears would have likely come with taller tires too the 255/50/17 "SS" tires were 27.04" tall where I think the regular cars got 245/70/15 which is something like 28.5" and that drags rpm at 150mph all the way down to 3600rpm the engine would be unlikely to make enough HP at such a low rpm to get the car to that speed and I suspect aerodynamic drag would stop acceleration well before that.
Trying to hold third gear would be 5100rpm at 150mph but the speed limiter, and factory rpm limit wont let you do that as well as needing to consider if such tires are rated for such speeds.
Actual rpm you see at these speeds will likely be higher due to torque converter slip but this is the "simplified" version and you can see that with overdrive rearend gearing and top speed do not act as most assume.
On the ABS thing there are reluctors available to let you keep the ABS functional, GM even made them for 3.42 and 3.73 and custom were made for 4.10s. It is additional cost but completely doable.
