1968 convert barracuda exhaust tip question

I am about to have an exhaust done on my 68 barracuda. I want to do the stock style tips, but Looking at the rear valance (below rear bumper) it appears that the valance should be cut to accept the square stock style tips. Is this true? any way around cutting a fresh painted valance? (the car was original single exhaust) or do I just find some knock off autozone tips. I was looking at a few sets on ebay for like $129, anyone used these?