We have welded up a few hundred of them over the years for the boat repair shop next door to our shop,, much like the video Rich posted, we always used wet rags to keep the gear housing cool,,, now they have a heat stop paste that works really really GOOD!! https://www.eastwood.com/coldshield-thermal-paste.html?fee=7&fep=2404&SRCCODE=PLA00020&product_id=13904&adpos=1o1&creative=83580267540&device=c&matchtype=&network=g&gclid=CIfNqKSh0tACFYVgfgodlroPgA ,,, mite get some for yourself for pieace of mined and have your welder use it,,,, dont think you would have much to worry about not useing it, your break is not that close to the houseing,, just have them make sure its cooled during the welding, we always welded half of one side then cooled it off the fliped it welded the other side half way the cool and flip finished the other side cool and flip finished and cool,,,, no real need to remove the lower unit unless the welder cant get the boat close enough to his machine,,,, shouldnt take someone much more then a half hour to do one,,, if you were to bring it into our shop would charge $50
Saw a pic of a Macs river runner prop guard hanging on it?? and it still broke????,, always wondered how they work,,, how did the prop fair???