New cam for my 318

That should be a fine choice. I'd look to replaceing the rear first, just my opinion. If you swapped out the rear for a 8-1/4 and added gear , you could increase the cam and performance thereafter.

IMO, it would be money well spent and not, "Well... (just) spent."

i agree with this. A swap to an 8.25 with 3.21s or an 8.75 with 3.23s would probably give a bigger performance boost than any cam swap at this point. And your 7.25 is probably on borrowed time. A 318 with stock converter and 2.76 gears is very easy to overcam and if you are not careful you could end up with a car that won't break the tires loose from a standing start.