Re: Tips for lowering CG and the whole car...
Find the stock rate on your springs, it is probably way soft for race use. I'd go 2-2.5x the stock rate and lower it as far as you can without ruining your geometry. Once you find the rate, length and ID or OD of your springs go to a spring catalog for Moog or one of the other suppliers and find an 80's car that has springs close to what you want. Then a quick visit to a junkyard and you have your springs. That's how we got the springs under the Lincoln so that it finally turns instead of just sliding arou8nd like a drift car.
Or you can check with the used race car suppliers, they have springs for cheap ( $10 - $15 bucks ) and they are measured for rate already.
If you are already re-welding your suspension pickups, you could move the pickups up to lower the body while keeping decent geometry. Watch for changing the steering linkage angles
1993 Linco Mark Ate
1957 Renault Dauphine
Driver with LemonSpeed's V6 Mustang