Is my engine dead?

Whoops! Thought you had a 360. KB167 is the part number you would want for some flat tops. Adam makes sense regarding the carb/manifold choice as the TQ has small primaries, although I'm a holley guy and I don't have much experience with the TQ's.

If you wanted to save some dough, the stock 4 bbl mopar manifoldis not all that bad of a piece although the performer (not the performer rpm) should give the low end a boost due to the smaller runners.

On the subject of low end torque, if your heads are in bad shape, you might want to see if you could find some 5.2 magnum heads and do the conversion. They are closed (small) chamber and a nice big quench pad. They'll boost your compression and add detonation resistance too as long as you set your quench to .040 with flat tops, a zero deck height, and .040 thick gasket. You can also use chevy style adjustable roller rockers (be sure to get the 1.6 ratio arms, as that is what the magnums used stock, and if you don't, you may have pushrod/head interference issues). The only problem with this swap is that your intake manifold choices would be limited.