Keep in mind the lighter springs only let the distributor go to maximum advance sooner, heaver springs later in the rpm range, they will still reach the same maximum advance eventually, but if the springs are too light the engine can advance too soon, if the engine advances too soon it can place added load on the engine (bogg) and also create and pre ignition
The vacuum canister is changeable and is what controls total vacuum, most are adjustable via an Allen wrench screw inside the vacuum tube port to fine tune total advance.
If you went for a drive before and it wasn't bogging (post 705) but now with timing changes its now its bogging and possibly has pre ignition which sounds like an exhaust leak at times then maybe its not the carb, maybe its too much advance per a given rpm range and/or also too much total advance. A step heaver on the springs Or reduce your total advance down to 28-30 or try a heavyer set of springs.
I want you to understand where I'm coming from, the more powerful the engine the less total advance it needs, I have this page stashed away in my faves, give it a read:
http://www.badasscars.com/index.cfm/...d=76/prd76.htm
Now with all this lets look at the carb issue, on post 705 i'm going to quote you as saying the following...
"When I drove it out onto the main road it was running great and felt very very powerful much more power and torque than before. I drove it for about 25 minutes so I can watch the trans temp gauge and engine temp gauge and everything stayed nice and cool no matter how I drove it. The throttle response was pretty good and even when I was in third gear at low speed I could stomp it and it would pick up and go pretty good"
If the carb was this close before the changes you made in the timing are not going to affect the carb that much!
If the carb is too lean its going to surge not bogg, if its too rich your gonna see some black smoke out the exhaust, you have a bigger engine which may require more fuel on the top end (mains) it is possible that the primary's may need to go a size larger or the metering rods adjusted or changed. but without doing any plug readings or having it dyno tuned with an exhaust sniffer your just taking pot shots at it.
Yea i still think its about the timing.