That is sometimes the disconnect between thinking you did something beneficial and actually finding the proof of it. If this 155 was discovered on a dyno, is it an actual reading or a factored reading adjusted for density altitude and dew point? Texas has a mean elevation of 1700' and nasty ass humidity. Where are you at relative to those factors?

Air flow makes power, so pumping more in with bigger heads and more cam lift and duration helps power production. Problem with your current configuration is you do not have the enough compression to utilize a big increases in air flow. Putting big heads and cam in this combo will make it lazy and less powerful than it already is.

Fine tuning of ignition curves and the carb, might get you closer to 200. If you can find the cam specs and get a cylinder pressure reading, you may be able to use that to talk to a cam company about options you might have. An RV style cam with low duration and high lift might get some extra air in without sacrificing cylinder pressure. Degreeing of the cam would be a big part of setting this up to build the most cylinder pressure.