Couldn’t agree more with having that back in the day feeling. I had a friend in high school (the guy who owned my cat before Dad) who had a Fairlane GT 390. With a cam, good high rise intake, port, polish, and mill on the heads, that thing was BRUTAL. He was running a 4.10 gear (small town w/everything 5 min away and very little highway travel), and 1/4 mile wise was one of the fastest cars in a line of very fast cars for the time. He still has the car and it is still as nice as back then along with another fairlane with a 427. If you want to go sleepy but be REALLY fast then have the intake and exhaust manifolds worked like a F.A.S.T car, and go with a custom grind cam. They run REALLY quick on stock tires, but if it were me I would just enjoy it as is, or maybe go with a little bit of a mild cam, and have a fun street car that will live all day in traffic or at freeway speeds. I might go with the ignitor under the stock cap, just for reliability. Even then a properly adjusted set of points will run great. Maybe mess with your timing curve and match it to your new gearing (yes you can do that), and also play with your jetting. I’ve found anywhere from 15-30 horses in tuning a car. You WILL feel that and even though you are getting it overhauled, won’t have to do anything that will be out of line with keeping it stock. Honestly, with an overbore, head/block milling and the upped compression that comes as a result of it, you will not only gain some but could also benefit from some razor tuning as well.
I really like the smaller FE engines, and have never found them to be deficient. Heck my other buddy had a late '60s pickup with a 390 that ran like a scalded dog stock with a two barrel.