US local newspaper obituaries in the nineteenth century frequently provide a good deal of information on parents and locations where people migrated from. As the person you are researching had pretty commonplace names you might very likely find multiple candidate families in Wales unless you have more background information that will enable you to differentiate your individuals from others of the same names.
To put the problem into perspective, 3.3% of the population of south Wales was surnamed Lewis in the nineteenth century; 1.5% of the population of north Wales, reaching a maximum of between 5% and 10% in certain areas (J.Rowlands & S.Rowlands "The surname of Wales", 2nd ed, Llandusul, 2013, pp.168-170).
When checking US local newspapers, try and check every title published in the relevant county; if they lived close to the border with another county then check newspapers published over the border also.
Good luck with your research!