5 Speed Gear ratio advice?

IMO
Swapping out the cam without giving it chance, is perhaps a bit premature.
You don't actually have to know the cam specs of a previously-installed cam, to know if it's right for you. You just need to drive it for an hour or two, it will become apparent.

Cams come in three flavors 1) too big,ie racey and 2) too small,ie good for fuel economy and torque, and 3) just right, ie street warrior. Within each flavor is a 2 or 3 cam size spread, with perhaps a streeter having an extra one or at most two.
There are only approximately 8 or 9 sizes to choose from all together, running the span from about 240 to 300 in about 7 degree steps. So for economy, one might choose from 240 to 254. And for racing one might choose from 284 to 298 or a bit more for a dedicated guy.
For a streeter we have from 262 to about 284,perhaps 292 for a guy who can make it hook. So that makes a middle of the road street cam about 273. When you go smaller than this, low speed power picks up, and with that comes fuel economy and enough vacuum to operate powerbrakes. When you go bigger than this, high rpm power picks up, fuel economy takes a dump,and the shift-rpm rapidly climbs into the stratosphere, especially with an automatic.
In a specific engine,each cam size will move the power-peak up about 200 rpm, and that is what creates the additional horsepower, cuz as you know, horsepower is a function of torque times rpm. Of course the heads have to support the airflow to make it work.
So choosing a cam should be as simple as choosing the rpm of peak power and grabbing the closest stick that promises to make it happen.
Unfortunately, the engine has to be built to survive the shift rpm. Choosing a cam that power-peaks at 6000, and with a 3 speed automatic, will mean the shift rpm will have to be tickling 7000, and that is a special build to survive.
Building a SBM to survive the occasional blast into the low 6000s by contrast, is relatively tame.
So perhaps a streeter would be wiser to choose a maximum sized cam according to the shift rpm. To that end one might choose 6200, cuz any SBM will survive that as a streeter. That, with an automatic, means a power peak of about 5000 to 5300. And that points directly to the ever-poplar 268* cam, to perhaps,magically, a 273 middle of the road cam,lol. There is a reason that cam is so popular.
A stick car can go one size bigger, cuz the rpm drops at the shift are less. Maybe even two sizes bigger, cuz compression braking will keep the manifold vacuum up during braking to operate the booster, and he's no sitting at the stopite with the engine tugging on the brakes. So that makes 284 about the max for a street SBM with a stick. I say about, cuz ,there's always somebody who swears by the 292,lol.
So that's all well and good, but what about that unknown-already-installed cam. Well there's exactly three things you want to know 1) where is the power peak, and 2) how rapidly does the power fall off,and 3) will my engine survive the trip. And for some 4) does it make enough vacuum to operate my booster for the duration of at least one stoplight.
To find the power peak, you have two or three options. 1)The cheapest is timed runs over; a measured distance,a specific mph range,or a specific rpm range. Not exact, perhaps, but doable and accurate enough for a streeter. 2)And very convenient is the windshield mounted accelerometer. Convenient cuz you can throw any mod on your engine and then run it one time, and see what happened, better or worse.3)and finally,the most expensive is the dyno.
And then there's the combo. The bigger cams rob low speed torque, which can be mitigated with some combination of compression, stall, and gears.

But the simplest of all to see if it suits you,since it's already in there, is just to drive the car.

But I still like post #28