Not sure what to do

For a small-engine street car,
like a 318, the Biggest bang for the buck is stall,
with rear-gears a close second.
It's hard to beat 4.10s and .69overdrive; don't even care about stall with those gears.
If you go down the road of engine hop-up, sooner or later you'll be wishing for overdrive. Not just for hiway cruising, but for the big rear gears you're lil 318 is gonna be hungry for.
With a stock low-compression 318,
I don't care how you combo it up, I guarantee you that all too soon yur gonna want a higher stall and/or rear gears. Every time you cam it up, you're bottom end is gonna go away, just a little more. Yur gonna have to stall it up and gear it up, just stay even in the lower half of the rpm band, where your sweet 318 is gonna be spending most of it's life; cuz if you don't, pretty soon it's gonna be nothing but a weekend warrior, and a miserable gas-guzzling pos hiway cruiser, parked in the carport.
Do yourself a favor stall; it up first, then gears; You'll never be sorry.
-----and then overdrive; now even less, not sorry.
-------then a 4bbl and hi-flow exhaust; now we're talking!
-----------Then, finally, yur ready to begin sacrificing cylinder pressure.

Or you could just pump up the compression first to match whatever cam you have chosen; Then stall it up, and gear it up, and so on, and then several thousands of dollars later, in goes the overdrive.
And then, you get an epiphany;
with 4.10s and a nice convertor, now yur just roasting the tires. You might as well give up a bunch of power cuz all it's good for is roasting said tires and sucking gas; and with the chassis as it now stands, you couldda done the same or at least not much worse, with say 250hp.
Ok hang on, that's about what a stock low-compression318 makes, with a 4bbl/hi-flow exhaust, and a tune.
If you keep your car long enough, you will have talked about overdrive, for nearly as long, and until it goes in, you'll be wishing you had installed it a loooog time ago.
Ok well, that's been my experience. lol.

If I was to start a 318 project today, knowing what I now know, over 50 years since being a teenage hi-school drop-out, the overdrive would be my first mod; followed hotly by probably a 3.91SG.
Then I'd plug a stock 5.2 in there, or a 9/1 LA, with a 5.9 type cam, headers, Free-flo exhaust, a small 4bbl, gotta have FRESH AIR, and call it done.
And this time Ima running short Cherry-Bombs! Hellya!