360 pros & cons vs 318

If you want it to scare you, shoot it with a 250 shot of nitrous THAT should scare the crap out of ya., my 74 duster came with a 318 and 904, put in a 360/727 (now 412) in 1983 and never looked back, I have 3:55's and it runs 3500@ 70 mph, I would leave the 3:23's in if you are going to drive it on the highway, if not then go 3:91.
I also agree go 360.