G'day vint_mow,
I'd say that this starter style was original to some of the larger Briggs engines, rather than a retrofit item.
The 1981 version Briggs Repair Manual shows this style of starter as having been fitted to engines in the 140000, 170000, 190000, 250000 and 300000 Model Series; i.e. 14 to 30 cubic inch.
The Impulse/Windup starters were only used on early 6, 8 and 9 cubic inch engines. Briggs used a different cowling for the Recoil Starter on these models, with the starter housing spot welded to it, as usual for their smaller engines.
For example, check the IPL for the Model 81706 engine;
http://www.thepowerportal.com/ipls/ipl.htm?md=081706944821_IPLURL_LO.pdfThe 6 in the Model Number denotes the Impulse starter here, but the other types are also shown in this IPL.