Making it a better driver

If a stock running 6 is enough for you than that fine tune it and run it but doesn't sound like it.
Hopping up a six is different than an eight not a lot of untapped power in one. Cam carb and headers can do a lot for an v8 but probably get you another 30 hp if lucky in a /6 add deep gears and could be fun which will defeat the 70-80 cruising speed. Unless you mill and port the head $$$$$ for some more power but still may come up short on power over the stock 360 depends how far your willing to go.

/6 is a cool engine I would like to build a sleeper 6 one day but it's not a cost effective engine even for mild performance even a 273 has way more power potential and mileage capability.
So except what you got and with tune and some mod get a tiny bit more power but if you want the cruising power of a stock v8 than there's really no other way plus you can add a OD down the road.