8.25 Gearing and Posi

What engine?
Jus Asking?
My guess is she's a heavy 318, A/C car with all the trimmings,

If that's true;
1) your first purchase should be a higher-stall convertor, something like a 2800, cuz those 74s were turd-engines. and 18% more gear, just means yur into Second sooner and back in turd-land.
2) your second install should be a small 4bbl.
3) now yur ready for gears,
But 18% more gear, points to 9% worse fuel economy.

Your call.