Which would be worse? Designating PA 43 as Interstate 97, or designating US 219 as Interstate 67?
Definitely the former, because there's already an existing I-97 but no hope that it would ever connect to PA 43. At least US 219 is a reasonable long distance corridor for I-67, and there's a legitimate case for an interstate on that corridor, even if it's an extreme long shot.
I say the latter, because although US 219 could one day become a full-fledged Interstate-quality freeway, I wouldn't dare propose any numbers for it because none of the possibilities are a good fit for it (my apologies to the late John Murtha), and all hopes of designating the corridor as one have apparently died off. Save I-67 for the US 31 upgrades north of Indianapolis.
U.S. 219 north of Johnstown is one of four highway corridors in western Pennsylvania that I think should be upgraded to four lanes, but not necessarily controlled-access. Upgrading U.S. 219 would better connect Johnstown to the I-80 corridor, and Bradford to the rest of Pennsylvania. Another U.S. highway that I think should be upgraded is U.S. 322 from the Ohio state line to State College. It'd better connect Erie and Meadville to the rest of Pennsylvania, and State College to areas northwest. Upgrading U.S. 219 and U.S. 322 would also give DuBois a boost, being the crossroads of three major highways. I also think it'd be a good idea to run U.S. 322 concurrent with I-80 from east of Clarion to east of Clearfield, and the existing U.S. 322 upgraded and designated U.S. 322 Alternate or U.S. 322 Business.
The other two four-lane upgrades I'd like to see are U.S. 30 from the West Virginia state line to Pittsburgh International Airport, and PA 28 from Kittanning to I-80 near Brookville. Upgrading U.S. 30 would create a high-speed highway corridor from Canton, OH to Pittsburgh, and I think realigning U.S. 30 to begin its concurrency with I-376 at Pittsburgh International Airport would be a good idea too. Upgrading PA 28 would provide another option for traffic traveling between Pittsburgh and New York City/New England. For that matter, PA 66 can become an enhanced two-lane highway with wider shoulders and higher design standards north to Clarion.