will this cam fit it 318

Marland is spot on. No replacement for displacement. However, the old 'swap in a 360' path has been well-trodden so I'm gonna press on with the 318 idea...
Okay, what you're looking for is a matched package. Firstly, that means that the cam, heads and intake must be matched to the compression ratio you run. A bigger cam needs more static compression, as the intake valve closes later in the cylinder stroke (as the piston is travelling back up the bore) so the dynamic (actual) compression will be reduced.

If you don't plan on swapping pistons or getting the heads cut then a short duration cam is by far your best bet. With a big cam your motor would work reasonably at higher rpm but with a huge loss of torque at lower rpms.

Also, the torque converter should be matched to the torque characteristics of the motor. If you are keeping the stock converter then once again a mild cam producing plenty of bottom end and mid-range will suit the combination far better.

As the gearing is an unknown, and you must assume they're quite long, once again torque is your friend.

I can't see any downside to fitting a shift kit though. I'd go right ahead and do that.

With all the above in mind, and your 'Comp Cams' requirement I'd go with the XE262. The duration is short enough to keep the dynamic compression up, it will build plenty of mid-range torque and still provides plenty of lift for a nicely ported set of 318 heads.

I absolutely wouldn't go bigger than a 600 carb with this set-up though.

I've been down the low compression, big cam route with the 318 in my anglia. I inherited the motor with TRW forged pistons about 70 thou 'down the hole', a Performer RPM intake mismatched to the intake port size, and a 650DP carb. The worst offender was the Performer RPM cam kit. All with the stock converter. It would pull past 6500 (and quickly, with 2500lbs weight and 4.11 gears) but I don't think it would have spun the tyres if I'd had them teflon-coated.