Mild Torque 318 suggestions wide open!

People somehow got the idea that strangling your engine gives you torque and adding free flowing parts gives you hp.

Hp and torque really ain't 2 different things.
Hp is just the sum of your engine torque and rpm abilities.

Unfortunately it's hard to increase torque of a N/A engine. Stock engine produce 1:1-1.1:1 lbs-ft per cid, a mild engine might get .5 more or so but without good flowing headers, heads, carb, intake etc.. it's hard to get more, even well built engine will struggle to get more than 1.35:1 lbs-ft per cid.

As you can see torque (low rpm hp) is tied heavily to engine size.

To me the trick is on a low performance engine (under 300hp) or any street engine is how far can you stretch the powerband without moving it off or too far from idle.
Obviously increasing the need for stall and gears if moved too high.

But really no needed to over think your build.
Stock 318 heads can get you 300 hp no problem. Any idle-5500 intake with a 650 ish carb. No need expensive manifolds 340 Will add 5hp at most so any 360/5.9 will do even 318 will only cost less than 5 hp.

So your engine build really just comes down to cam an cr choice. CR you'll probably want 8.8-9 to one. So that leaves just cam which you'll want a stock 340 ish cam or a modern design around 250-260. Especially one designed with manifolds in mind.

Now heads stock will more than do but you'll leave power one the table or make the same with a little less cam. Could doing a little porting on the 318 heads or upgrade to 360 or magnum heads.

For this low level build I'd start with magnum 5.9 or even the 5.2. They both make around 300 hp gross and almost you goal net.
So all you need then is to rebuild to stock and maybe a cam regrind to add a bit more power. If you could keep the beer barrel efi it actually increase the low end quite a bit and can tell you from experience (5.9 jeep) has lots of bottom end.