I Purchase the Spectrum Premium GM307C, This one is used mostly from the GN Guys, The metal Baffles inside the tank is the closet to original. If you planning to do this to regal, this tank is your best choice. The Tank is made in Canada, That the C at the end of the part number. I order mine from summit racing, but i found the best price out there and price match with them. They also price match from eBay as long its a commercial seller. Did the same with the Sending unit. and used a Aeromotive fuel pump. I hope this help.
I paid: Fuel Tank GM307C - 133.96
Sending Unit FG156A - 80.34
Aeromotive Pump 11569 - 112.95