I once did the simple conversion to 5-lug FRPP brakes. Still tiny little rotors and brakes, but got me the 5-lug I wanted:
If you wish to upgrade the stopping power, then 73mm calipers are a shortsighted and cheap suggestion.
If you relly want brakes, then get M2300K Cobra 13" front brakes. I ran these for years.
Then if you really, really serious about brakes, take the final plunge and spend the money on 2000 Cobra R Brembo calipers. That is my final brakes, I swear (for now...).