I'm in agreement with most of the others here, get it on the road and enjoy it like it was meant to be enjoyed. If you go the rotisserie restoration route it will be extremely expensive, and you may not want to drive it after spending a whole lot of money on it, which leads back to it sitting neglected. Get the 340 together, you can put fuel injection on it for ease of drivability and reliability, or as some have suggested, drop in a Gen 3 Hemi with an overdrive transmission. It depends mostly on your budget, your abilities and skills, and what you ultimately want out of it. Guessing it was born with a 318?
Just my .02.