340 in 68 dodge dart 4 door?

Hi guys. I am the old guy in this jordan&carl team. Ran an Olds 442 in late 70s on the street and strip. Had a Friday/Sat nite Main St cruiser(71 Duster with 340) in OH and a 76 Power Wagon with 360 when I lived in CO. But I took out the 360 2 barrel and built a stock 318 with 4 barrel adding power and even better gas mileage.

In CO, I worked at an underground coal mine and also had an auto repair business on the side. Not much sleep for about 18 years until I got this corporate job. LOL Just been out of the loop sorta for a few years.

Jordan asked about a 360 and I can understand your thoughts of engine and parts availability.

Two things come to mind as questions.
1. Would a 318 be as good a choice over the 360 as a mild buildup for street driving? Are the parts and engines as available as the 360?
2. Our Dart has a 225 with small auto trans. When we go to a V8 what is your recommendations for a trany upgrade? Not sure what type of tranny is in it now.

Thanks for the help