new cam install

[charger72]

i just put a new cam into my 77 truck. It was supposed to be a comp towing cam, but after it is installs and am using it it seems alittle weak in power like it should. i found out ot is a super stock cam. specs are... .280 intake, .290 exhaust(lift) .420, .443 advertised duration is 270intake and 280exhaust. duration 204intake, 214exhaust.   
I was wondering if t his is a good cam for truck or not? i was going to use Engle, but it seems alittle hogh for a price for theirs.

[charger72]

also, the motor is a 318 with a fulltime transfercase, auto ans 2bbl carb.