225 to 318 or 360 LA

Wait, is this a trick question?.

First things first; what are you gonna do for traction? You can't put much tire back there in the stock wells. The 360 will want some serious rubber and traction aider, the 340 a lil less, and the teener will get away with the least.
So if you just like buying skinny tires, the 360/904 is way to go, and if you don't put slicks in there , the 7.25 with an LSD will do pretty good. But if you tub it and manage to install 295s, well then the 360/904 will want at least an 8.25SG.
But if you are gonna leave those wheelwells stock, what would be the point of the 360, except to really, really, really annihilate the tires.

But then there is OptionB. The 360 in your application can be set up very mildly, and then run 2.94s for really great gas mileage. The mild engine will have more than enough oomph to motorvate one of these lightweights, on a par with a hopped up 318.
A small cammed 360 with;2.94s, a 2.45 low/904, and say 26.5" tires, will do 65@2460rpm, and first gear will do 60@5566rpm. And a 2200stall will get things moving in a hurry.That TC might be the stock one.If you choose the right parts you can have a heck of a combo; doing both performance and economy.
And then there is OptionC. I recall, in 84, Chevy came out with a 305 pick-up.What a gutless wonder that thing was. But the thing I really remember about that beast was, with a bit of weight in the box,with a cap, and three-abreast in the cab; If you floored it,the TC would jump up to around 2400(going by ear, and memory), and then it would kindof just hang there all the way to September. Kindof like a computer-controlled CVT. I always thought that was cool. Ok so now imagine a 273 with a tiny 2bbl hi-compression and headers with a pair of cherry bombs, and shot-gun pipes out the back. And the absolute tightest TC you can find;like 1800.And say 2.76s.Then program the governor to shift bam-bam-bam; Into hi real early. Now floor it. TC flashes to 1800, car "blasts" off, TC settles down to a little less, and bam into second it goes. And a second or two later,bam, into hi gear. So now you are at 50mph@2000rpm and so begins the long march to 65@2280rpm. Yeah,ok, that's a bit slow for me too. But cool non-the-less. Ok so do it with a 360 and and a small TQ carb,less compression, a semi-auto shift VB and a 2200TC, 2.94s again, and wind up the secondary air-door a little on the tight side. Same deal, but now, when you're in a hurry you just hold it in gear a lil longer.
And then there is OptionD. or E,F G etc.
What are you thinking?
I'm thinking;360 or nothing.But don't be chasing a horsepower number; your car will be already near well under 3000 pounds, so even a dog360 will have no trouble motorvating that! but if you pump it up, it will be big-fun. And then begin the upgrades for safety sake; suspension,steering,and brakes.
But I just gotta stress one thing easy on the cam selection.