Any parts to get my Cuda good gas mileage (other part listed)

hi! So I'm looking to be able to drive my 1966 Barracuda to Los Angeles, from Northern California, 9 hours away. I know most definitely that I need a radiator, so if you have one out of any car that you know will fit a 225 Slant Six AUTOMATIC 3 speed, I'll buy if it's a good price.
also looking for any other part that help my car get better gas mirage and make the drive. Ideally I'd like to drive it down and back once a week or once every two weeks, for 3 or 4 days then come back up.
Now, is this Recommended? Are older car just not safe anymore? I'd love to drive my Cuda down, so please, any info to help me, (who's on a low budget) driving to la would be appreciated. Ideas, thoughts, info, advice, or parts for sale for cheap I'd be interested in! Please private message me, just seems to be more easy for me.

also, parts I'm looking for:
Idler arm
Rear tail light lense set (all) and bulbS
15 inch wheels and tires combo, for 5x4" small bolt pattern not 4.5"!!
Starter relay
Locking gas cap
Petronix
One barrel Holley carb
Gas sending unit for inside tank

image.jpeg

image.jpeg