Need more Vroom from my 350

[walker]

I don't know who might remember my SBC saga but in the end I put in a GM crate 350 into my '67 LWB C-10, out of desperation. It has a performer intake, edelbrock 600cfm, stock exhaust manifolds, mallory HEI. It was running poorly as of late and I looked into it tonight and found that my advance wasn't advancing. I got the advance working, and advancing to what I would guess is about thirty something BTDC, it started pinging so I retarded it a little. It left me wanting a little more horsepower though.
So here is my question, what are the steps I can take to get the power. I have considered going to a TBI set up for easier starts, more power, better economy. Don't get me wrong I am not trying to get 30 mpg, while burning rubber, or anything like that, but 14 mpg would be nice, and fuel economy is not a huge concern for me. But I would like to hear some more options. I would love to have a blower motor but don't think that fits in to my life right now. I have a pair of dart heads left from my last engine, only have a couple hundred miles on them(long story). They are a 196intake 160exhaust 76ccintake, to the best of my recollection. Would it make sence to install these heads? I am not sure what type of heads the GM crate 350's come with, although I can't imagine that they are anything but smoggers, so I don't know if this is a good option or not. Also, the TH400 has a stock converter in it. It has such a low stall speed that I have difficulty in breaking the tires loose, even though I have 4.11's in the rear. The exhaust system has been replaced with a dual pipe system with turbo mufflers, from one of the vendors.
If anyone has some good options for me I would love to hear them. Thanks, Andy.