4 Speed w/ Overdrive Any Good?

I currently have a 383 4 speed, which I thoroughly enjoy. The problem is I like to drive this car alot and a 5th gear would make it more drivable.

So, would a 833 with overdrive be a good replacement?
Do they have the ability to hold up to a stock 383?
A rebuilt or hopped up 383?

Can I use the Hurst shifter I currently have on my 4 speed?

Is it a direct swap, bolt right in?

Any info would be helpful, there is one for sale near me and I am considering it as a way to get more mileage out of my car.

Casting number PP833 5330 with a 10 bolt cover number 99386 C99129.

The guy wants $650.