In the case of your Morgan OI 33, if she does not appear to heel much it is as a result of whole bunch of reasons which have very little do with the type of keel that she has or the fact that she has a comparartively low-ballast to displacement ratio for a shoal draft boat.
In the case of the Morgan 33, these are very beamy boats, with small sail plans for their displacement. They also have a lot of freeboard so that the heel angle does not seem all that extreme since the rail remains high above the water at pretty large heel angles. In fairness though, designers like Charlie Morgan, Ted Hood, and Dieter Empachter were all able to model comparatively heavish displacement designs that are less drag than might otherwise be expected. Hood and Empachter, made up for the extra displacement with comparatively high ballast ratios and generous sail plans.....Morgan on the Out Island series, not so much.