Be careful with what "everyone is talking about."
It is true that many engines from the emissions-regulated portion of the muscle have rather slow advance curves but none of them had springs such that full advance was prevented. If you change to lighter springs, the spark advance will occur more quickly, but the full advance will be the same.
Generally, performance tuning for engines from that era respond well to a quickened advance curve and sometimes an altered advance limit. But...your results may differ.
There are four different mods one can make to a Delco distributor
1) change the springs
2) change the advance weights
3) change the advance limit bushing
4) change the breaker point cam to one with a shorter limiting slot.
#4 can sometimes be quite useful but it is very difficult to acomplish these days because the parts to do it are very difficult to acquire.
Typically, with emissions era distributors, to gain some performance and response, you want to quicken the rate of advance, reduce the total advance, increase the initial advance and limit (but not eliminate) the vacuum advance.
A typical curve for a low-compression 72 engine, might be 36-38 deg. total (24 in the distributor and 12 at the crank) all in by 2800-3200 and a vacuum advance limited to 8-10 deg.
