Not thrilled with power from new 350

[AirSpeed]

Recently installed a crate 290 hp 350 in my 72 GMC 4X4 with th350, after a fiasco with broken valves in the first one delivered I got the second in and running. Broke in the cam, have been driving as GM suggest so I haven't really had the nerve to floor it yet but what I'm feeling now is a little disappointing. I have decent power after about 2000 rpm, my trans seems to shift better than ever but low speed power is not there. As I said I haven't really got on it at all but it feels like a dog.
I'm running the stock intake and quadrajet and an HEI out of an 80's truck. After I ordered the engine I was told by a few people here that I would have been better off buying the 250 hp version but of course it was to late.
I am curious if I'm going to be happy with the power after I have it broke in enough to drive it harder, anyone here have this engine in a similar configuration? Are you happy with it? Whst can I do to this engine to squeeze more power out of it? I really don't want to pull the heads or change the cam. Will an aftermarket intake help? New carb? What else can I do to it?
I don't have a lot of money to spend on my truck after just buying new tires then having my engine take a dump so I'm looking for cheap upgrades! Any suggestions on cheap and fairly easy power upgrades would be appreciated! I'm also interested if others with this engine have had similar issues? Thanks!