The TBI will excel in 1 area over the 1920/1945: All weather start up. A guy did a GM TBI retrofit on a slant and didnt gain anything (MPH/torque) except a easy to start slant! mind you there is little to tune on a stock GM unit but its not a bolt on +25% venture. MS/Holley/ETC will allow you to tweak many parameters and timing. I think the latter is the seat of the pants key to an improved conversion. Holley 1920 had great functionality, as it had a very small venturi and had very high velocity in the intake. Slap a 2bbl TBI with 2 1-3/8 or 1-13/16 non staged bores and your going to really drop velocity which carries the fuel in suspension. you may want to look into a 1bbl TBI off an 82-86 GM 2.0-2.4, as your looking for HP levels, not necessarily displacement. You can always adjust fuel pressure up to boost the injectors output to a point.