Cam sizing

I got into this when I rebuilt the 727 behind my 340. I vaguely remember the stock 10" converter for a 340 is around a 2400 stall.
Bigger port heads off the 360 generally will loose bottom end torque on a 318 (possibly a bunch), but gain power at higher RPM if the car has the gearing to allow you to get to that higher RPM. Bigger port heads (J in this case) are going to be the best match to the 360 intake. Too much cam (duration and overlap) will give you a soggy bottom end and the J heads and larger port 360 intake on a 318 will make it worse. Spreading out the valve events (110 to 114 degree centerlines) will give less overlap at any given duration/lift and tame down any cam somewhat.
Staying with a stock spreadbore carburetor should give you just as much (or more) top end as a square bore Holley and be far more forgiving of the smaller displacement, too.