I’ve been asked more than once if one could take the changes I made in Microlite74 Extended (such as Body Points and Hit points) and use them in Swords & Wizardry or OD&D? The answer is obvious — at least to me. Yes, you can.
Most of the rules changes in Microlite74 Extended were taken from house rules I used with OD&D in the late 1970s, changed where necessary to make them compatible with Microlite20-based rules like those used in Microlite74. The change most people seem to be interested in using with other sets of rules are the rules for hit points and body points (and using hits points as spell points). This system is needed few changes to convert to Microlite74. In the original, Body Points were equal to the characters Constitution score or 10, whichever was higher. Hit points were calculated as in standard Greyhawk OD&D. Spell Casters had to memorize spells normally, but could cast them as many times as they could power them with each casting costing the spell’s level + 2 in hit points. Otherwise, the rules as used in Microlite74 Extended are pretty much what I used in 0e. With a little fiddling, they probably could be used with any TSR era version of D&D.