So many questions so little time lol just kidding I think we can help.
1) FIRST OFF you need to Polarize the Genny BEFORE start up because if the genny is at opposite polarity from tractor you can damage the new Voltage Regulator. Theres a chance at the shop the genny was Polarized for Neg ground and your tractor may still be Pos ground. POLARIZE THE GENNY BEFORE YOU START IT AGAIN.
2) If it has a Voltage Regulator, its wired:
BAT up to ammeter in dash same as with a cutout relay.
FLD wires to gennys FLD post NOTE theres no longer a wire from light switch to gennys FLD post, DO NOT WIRE FLD TO LIGHT SWITCH WITH A VR
GEN/ARM on VR wires to Gennys ARM post
---Are you at Pos or Neg ground?????? Regardless Polarize the genny before starting next time.
---DO NOT wire gennys FLD to light switch, ONLY to new VR
---If you changed from Po to Neg ground, the ammeter leads need swapped and coil leads need swapped
---I wonder if the new VR is suitable for your tractor polarity??? Id wire the tractor to match the VR polarity and swap coil and ammeter leads if necessary for that polarity and POLARIZE before starting and if wired as abvove it may work and maybe the new VR wasn't damaged
--- FINAL NOTE if the new VR is a 4 terminal (BAT LOAD FLD GEN/ARM) instead of a 3 terminal (BAT FLD GEN/ARM) post back because on those GEN/ARM is often underneath or on one side all by itself and loads like lights and ignition are fed off the L terminal instead of the ammeter or BAT on VR