3/5 drop on my 84

[N2TRUX]

I think you might be close on the tire height. I have never lowered one only 3" and retained the tall tires so I can't be sure.

What I can recommend is to consider running drop spindles rather than 3" springs. Since your on a budget, I suggest a 2.5" spindle and a 1" spring. If that doesn't fit your budget consider the spindles and cut one coil off your stock springs. Just be careful when you cut them and don't get the springs hot.