As has been pointed out, Ed "Strangler" Lewis is essentially one of the three men responsible for he overall layout of professional wrestling as we know it today, with the other two men being promoters Billy Sandow and Toots Mondt. This "Gold Dust Trio", as they were often referred to, pretty much dominated pro wrestling during the 1920s. In terms of technical ability, Lewis was really the very first THE MAN" in pro wrestling and was Lou Thesz's mentor & teacher.
Kerry Von Erich was a pretty good example of the more modern depiction of professional wrestling: he made all the girls go wild, he had a fantastic physique, was a genuinely good athlete, looked like he could take someone apart but he had no real, legit technical knowhow.
Just by looking at pictures of the two, you'd figure that Kerry Von Erich would mangle this "normal" looking guy without much of an effort because, as humans, we rely far more on sight as a species as it's the most developed of our senses. Because Kerry Von Erich has a physique and stature that strikes pretty much anybody as more impressive, it's natural to believe that he'd take this far smaller, far less athletic looking gentleman apart at will but, in reality, that's simply not how a fight works.
Now in terms of sheer raw strength and overall athletic ability, Kerry Von Erich is physical superior and could wear Lewis down if Lewis didn't take him serious enough. If Lewis screwed around with Von Erich, it's not impossible to imagine that Kerry getting a win but I don't see Lewis screwing around with Von Erich's obvious strength and athleticism. That's not to say that Von Erich didn't have any grappling training of course, but Lewis was one of the all time great hookers in the business and there's no comparison in their technical skills.
Kerry Von Erich was immensely popular at one point when WCCW was genuinely one of the top promotions in the world. Kerry Von Erich's winning of the NWA World Heavyweight Championship always struck me as more of a tribute to his brother David won the title at the inaugural David Von Erich Memorial Parade of Champions event. Considering the show was generally promoted as a tribute, it needed that big feel good moment. However, he dropped the title back to Flair less than 3 weeks later and if I'm not mistaken, Kerry had begun developing or had already developed a reputation for being unreliable due to drug use and his reputation never really recovered. So whereas Kerry Von Erich's one and only World Championship run was ultimately little more than a vanity run to give fans a feel good moment, Ed Lewis' title runs were truly legit. Lewis' four runs with the early catch as catch can World Heavyweight Championship, the one won originally by Georg Hackenschmidt and would eventually be grafted into the lineage of the NWA World Heavyweight Championship, lasted a combined total of 3,057 days.
I think Kerry would surprise Lewis if Lewis just sorta dicked around with him but, otherwise, I think Lewis takes it.