Y'all need to fully research the LB system and how it changed from year to year, in order to "work around" it.
BUT, as I recall, ONE thing is that the advance curve calibrations are in the computer, not the distributor. So, if you unplug the computer, then whatever advance is then in the ignition timing is the BASE timing ONLY.
By the time your car was engineered, the TQ was becoming festooned with many "fixes" to decrease emissions. They all had their place, but could be troublesome in later life as that "wire" they were walking was becoming increasingly "narrow" (as to exhaust emission compliance).
The current Street Demon carburetor is pretty much a newer carb which copies the vast majority of TQ engineering, which is basically good and neat. There are also metering kits and such, too. I'd head in that direction. It'll also fit your existing intake manifold. Then add throttle linkage adapter Holley sells, too.
For ignition, several choices in the aftermarket. A stand-alone ignition system from Rick Ehrenberg, a rebuilt distributor from Halifoxhops (with some other complimentary items to make it work), or a DUI set-up. These things will get you a reliable system which is a distributor with internal "advance curves" rather than the distributor you have without any of that.
The DUI is compelling as it uses the common GM HEI module to run it, so if it is like the GM HEI, all it needs to work is a solid 12+Vole power feed (check its instructions online). There might be a kit to use an existing Chrysler distributor (advance) distributor and add the GM module external to it?
The ELB had two functions. A carb designed to provide an 18.0 to 1 air/fuel ratio at cruise (rather than the normal 14.8 ratio) and a distributor advance curve which went farther (as to advance levels) to ignite these leaner mixtures for greatly-reduced HC and CO emissions, and enough spark advance to get into the greatly-reduced NOx regions, too. The leaner mixtures take more lead time to get burnt before the piston reaches the TDC area, which is best performed by computers.
BUT no ignition system can work with a carburetor to attain good engine performance when there are vacuum leaks (which further lean the already lean mixtures!). Look for those FIRST, no matter what. Look for cracked vac hoses to the power brake booster, cruise control, and hvac system. Verify the hot base ignition timing, too. Check to verify the carburetor is snugged down to the manifold.
Additionally, the ELB system modulation works on "voltage and resistances". The throttle position transducer is similar to current Throttle Position Sensors (measures throttle position and rate of change via a potentiometer). The vacuum sensor (the vac line to the diaphram on the computer) measures engine load (idle, cruise, etc.). The idle speed connection (on the idle screw contact) tells the computer the carb is at hot base idle, so no advance functions. With these inputs, the ELB Computer configures a distributor advance map for best results of performance and emissions. There were also inputs from engine coolant temperature, ambient air temp, charge temperature (from an intake manifold runner), etc. Initially, it all worked well enough that the vehicles would pass their model year emissions without the need of an "after-treatment" catalytic converter . . . which was an accomplishment, to me. But in later years, converters were needed and by 1980 it all had morphed into a computerized system without the prior "lean burn" orientation.
The systems worked pretty well when new, but less so as time progressed. Rebuilding your existing TQ can be an exercise in futility when a new carb (as the Street Demon) will eventually be needed. Plus the full ignition conversion back to pre-ELB days with a distributor that has mechanical and vacuum advance in it.
Watch the post-Christmas sales!
Enjoy!
CBODY67
